Imaging apparatus and electronic equipment

ABSTRACT

The present technology relates to an imaging apparatus and electronic equipment that can reduce noise. A photoelectric conversion element, a conversion unit that converts a signal from the photoelectric conversion element into a digital signal, a bias circuit that supplies a bias current for controlling a current flowing through an analog circuit in the conversion unit, and a control unit that controls the bias circuit on the basis of an output signal from the conversion unit are provided, and at the start of transfer of a charge from the photoelectric conversion element, the control unit boosts a voltage at a predetermined position of the analog circuit. The conversion unit converts the signal from the photoelectric conversion element into a digital signal using a slope signal whose level monotonously decreases with time. The present technology is applicable to, for example, an imaging apparatus.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation application of U.S. patent applicationSer. No. 16/755,981, filed on Apr. 14, 2020, which is a U.S. NationalPhase of International Patent Application No. PCT/JP2018/037501 filed onOct. 9, 2018, which claims priority benefit of Japanese PatentApplication No. JP 2017-204203 filed in the Japan Patent Office on Oct.23, 2017. Each of the above-referenced applications is herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present technology relates to an imaging apparatus and electronicequipment, and to an imaging apparatus and electronic equipment that arecapable of adaptively changing a noise level and capturing an image withimproved image quality.

BACKGROUND ART

Conventionally, in electronic equipment having an imaging function suchas a digital still camera or a digital video camera, an image sensor,for example, a charge coupled device (CCD), a complementary metal oxidesemiconductor (CMOS) image sensor, or the like is used.

The image sensor has a pixel in which a photodiode (PD) that performsphotoelectric conversion and a plurality of transistors are combined,and an image on the basis of pixel signals output from the plurality ofpixels arranged in a plane is constructed. Furthermore, the pixelsignals output from the pixels are AD-converted in parallel, forexample, by a plurality of analog to digital (AD) converters arrangedwith respect to each pixel column, and output.

Patent Document 1 proposes an imaging apparatus that reduces powerconsumption and random noise.

CITATION LIST Patent Document Patent Document 1: Japanese PatentApplication Laid-Open No. 2007-151170 SUMMARY OF THE INVENTION Problemsto be Solved by the Invention

The noise level of the image sensor is defined by thermal noise, 1/fnoise, and quantization noise. In order to reduce the thermal noise, itis conceivable to improve the gm of the circuit, but this leads to anincrease in current consumed by the analog circuit, which can increasepower.

Furthermore, the 1/f noise is sensitive to current, but it is mainlydetermined by the area and the process, and measures for these can leadto increased costs. The quantization noise is uniquely determined by theresolution of the AD converter, but at low illuminance, it is defined bythe random noise of the image sensor itself and the quantization noiseof the AD converter. The thermal noise and the 1/f noise of the randomnoise depend on the amount of current consumed by the analog circuit.

The present technology has been made in view of such a situation toenable the current consumed in the analog circuit to be adaptivelyvariably adjusted from the AD converted output signal to reduce power athigh illumination and achieve low noise at low illumination.

Solutions to Problems

An imaging apparatus according to an aspect of the present technologyincludes: a photoelectric conversion element; a conversion unitconfigured to convert a signal from the photoelectric conversion elementinto a digital signal; a bias circuit configured to supply a biascurrent for controlling current flowing through an analog circuit in theconversion unit; and a control unit configured to control the biascircuit on the basis of an output signal from the conversion unit, inwhich at start of transfer of a charge from the photoelectric conversionelement, the control unit boosts a voltage at a predetermined positionof the analog circuit.

Electronic equipment according to an aspect of the present technologyincludes: an imaging apparatus including: a photoelectric conversionelement; a conversion unit configured to convert a signal from thephotoelectric conversion element into a digital signal; a bias circuitconfigured to supply a bias current for controlling current flowingthrough an analog circuit in the conversion unit; and a control unitconfigured to control the bias circuit on the basis of an output signalfrom the conversion unit, in which at start of transfer of a charge fromthe photoelectric conversion element, the control unit boosts a voltageat a predetermined position of the analog circuit.

The imaging apparatus according to an aspect of the present technologyincludes: a photoelectric conversion element; a conversion unitconfigured to convert a signal from the photoelectric conversion elementinto a digital signal; a bias circuit configured to supply a biascurrent for controlling a current flowing through an analog circuit inthe conversion unit; and a control unit configured to control the biascircuit on the basis of an output signal from the conversion unit.Furthermore, at the start of transfer of a charge from the photoelectricconversion element, the control unit boosts a voltage at a predeterminedposition of the analog circuit.

Electronic equipment according to an aspect of the present technologyincludes the imaging apparatus.

Note that the imaging apparatus and the electronic equipment may beindependent apparatuses or may be internal blocks constituting a singleapparatus.

Effects of the Invention

According to an aspect of the present technology, low power consumptionat high illuminance and low noise at low illuminance can be achieved byadaptively variably adjusting the current consumed by the analog circuitfrom the AD converted output signal.

Note that effects described herein are not necessarily limited, but mayalso be any of those described in the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a schematic configuration of an imagingapparatus according to the present disclosure.

FIG. 2 is a block diagram illustrating a detailed configuration exampleof a pixel.

FIG. 3 is a block diagram illustrating a detailed configuration exampleof a comparison circuit.

FIG. 4 is a diagram explaining a detailed configuration of a pixelcircuit.

FIG. 5 is a timing chart for explaining the operation of a pixel.

FIG. 6 is a diagram for explaining a configuration of a circuitincluding noise.

FIG. 7 is a diagram for explaining a configuration of a circuitincluding noise.

FIG. 8 is a diagram for explaining a configuration of a circuitincluding noise.

FIG. 9 is a diagram for explaining a configuration of a circuitincluding noise.

FIG. 10 is a diagram for explaining a configuration of a circuitincluding a judgement unit.

FIG. 11 is a diagram for explaining a configuration of a judgement unit.

FIG. 12 is a diagram for explaining a configuration of a bias circuit.

FIG. 13 is a diagram for explaining a configuration of a DAC.

FIG. 14 is a diagram for explaining a waveform of a signal output from aDAC.

FIG. 15 is a diagram for explaining a configuration of a bias circuit.

FIG. 16 is a diagram for explaining the generation of a backflow chargefrom an FD.

FIG. 17 is a diagram for explaining the generation of a backflow chargefrom the FD.

FIG. 18 is a diagram for explaining a configuration of a bias circuit.

FIG. 19 is a timing chart for explaining the operation of a pixel.

FIG. 20 is a diagram for explaining a configuration of a bias circuit.

FIG. 21 is a diagram for explaining the arrangement position of a biascircuit.

FIG. 22 is a diagram for explaining the arrangement position of the biascircuit.

FIG. 23 is a diagram for explaining a configuration of a bias circuit.

FIG. 24 is a timing chart for explaining the operation of a pixel.

FIG. 25 is a diagram for explaining a configuration of a bias circuit.

FIG. 26 is a diagram for explaining the timing of control.

FIG. 27 is a circuit diagram illustrating a configuration example of acomparison circuit in the case of pixel sharing.

FIG. 28 is a diagram for explaining the timing of control.

FIG. 29 is a conceptual diagram of an imaging apparatus configured by astack of two semiconductor substrates.

FIG. 30 is a diagram illustrating a circuit configuration example in acase where an imaging apparatus is configured by two semiconductorsubstrates.

FIG. 31 is a conceptual diagram of an imaging apparatus configured by astack of three semiconductor substrates.

FIG. 32 is a diagram illustrating a circuit configuration example in acase where an imaging apparatus is configured by three semiconductorsubstrates.

FIG. 33 is a diagram for explaining another configuration of a circuitincluding a judgement unit.

FIG. 34 is a diagram for explaining another configuration of a circuitincluding a judgement unit.

FIG. 35 is a diagram for explaining another configuration of a circuitincluding a judgement unit.

FIG. 36 is a diagram for explaining another configuration of a circuitincluding a judgement unit.

FIG. 37 is a block diagram illustrating a configuration example of animaging apparatus as electronic equipment according to the presentdisclosure.

FIG. 38 is a block diagram illustrating an example of a schematicconfiguration of an in-vivo information acquisition system.

FIG. 39 is a diagram illustrating an example of a schematicconfiguration of an endoscopic surgery system.

FIG. 40 is a block diagram illustrating an example of a functionconfiguration of a camera head and a CCU.

FIG. 41 is a block diagram illustrating a schematic configurationexample of a vehicle control system.

FIG. 42 is an explanatory diagram illustrating an example of aninstallation position of an imaging unit.

MODE FOR CARRYING OUT THE INVENTION

Modes for carrying out the present technology (hereinafter, theembodiments) will be described below.

<Schematic Configuration Example of the Imaging Apparatus>

FIG. 1 illustrates a schematic configuration of an imaging apparatusaccording to the present disclosure.

An imaging apparatus 1 in FIG. 1 includes a pixel array unit 22 in whichpixels 21 are arranged in a two-dimensional array pattern on asemiconductor substrate 11 using, for example, silicon (Si) as asemiconductor. The pixel array unit 22 is also provided with time codetransfer units 23 that transfer a time code generated by time codegeneration units 26 to each pixel 21. Then, around the pixel array unit22 on the semiconductor substrate 11, a pixel drive circuit 24, a D/Aconverter (DAC) 25, the time code generation units 26, a vertical drivecircuit 27, an output unit 28, and a timing generation circuit 29 areformed.

As will be described later with reference to FIG. 2, each of the pixels21 arranged in a two-dimensional array pattern is provided with a pixelcircuit 41 and an ADC 42. The pixel 21 generates a charge signalcorresponding to the amount of light received by a light receivingelement (e.g., a photodiode) in the pixel is generated, converts it intoa digital pixel signal SIG, and outputs the pixel signal SIG.

The pixel drive circuit 24 drives the pixel circuit 41 (FIG. 2) in thepixel 21. The DAC 25 functions as a generation unit that generates areference signal (reference voltage signal) REF, which is a slope signalwhose level (voltage) monotonously decreases with time, and supplies thegenerated reference signal REF to each pixel 21. The time codegeneration unit 26 generates a time code used when each pixel 21converts the analog pixel signal SIG into a digital signal (ADconversion), and supplies the time code to the corresponding time codetransfer unit 23.

A plurality of time code generation units 26 is provided with respect tothe pixel array unit 22, and as many time code transfer units 23 as thenumber corresponding to the time code generation units 26 are providedin the pixel array unit 22. That is, the time code generation unit 26and the time code transfer unit 23 that transfers the time codegenerated thereby correspond one-to-one.

The vertical drive circuit 27 performs control to cause the output unit28 to output the digital pixel signal SIG generated in the pixel 21 in apredetermined order on the basis of a timing signal supplied from thetiming generation circuit 29. The digital pixel signal SIG output fromthe pixel 21 is output from the output unit 28 to the outside of theimaging apparatus 1. The output unit 28 performs predetermined digitalsignal processing such as black level correction processing forcorrecting the black level, correlated double sampling (CDS) processing,or the like, as necessary, and then outputs the resulting signal to theoutside.

The timing generation circuit 29 includes a timing generator or the likethat generates various timing signals, and supplies the generatedvarious timing signals to the pixel drive circuit 24, the DAC 25, thevertical drive circuit 27, and the like.

The imaging apparatus 1 is configured as described above. Note that, inFIG. 1, as described above, it has been described that all the circuitsconstituting the imaging apparatus 1 are formed on one semiconductorsubstrate 11. However, as will be described later, the circuitsconstituting the imaging apparatus 1 may be configured to be separatelyarranged on a plurality of semiconductor substrates 11.

<Detailed Configuration Example of the Pixel>

FIG. 2 is a block diagram illustrating a detailed configuration exampleof the pixel 21.

The pixel 21 includes the pixel circuit 41 and the ADC (AD converter)42.

The pixel circuit 41 outputs a charge signal corresponding to thereceived light amount to the ADC 42 as an analog pixel signal SIG. TheADC 42 converts the analog pixel signal SIG supplied from the pixelcircuit 41 into a digital signal.

The ADC 42 includes a comparison circuit 51 and a data storage unit 52.

The comparison circuit 51 compares the reference signal REF suppliedfrom the DAC 25 with the pixel signal SIG, and outputs an output signalVCO as a comparison result signal indicative of a comparison result. Thecomparison circuit 51 inverts the output signal VCO when the referencesignal REF and the pixel signal SIG are the same (voltage).

The comparison circuit 51 includes a differential input circuit 61, avoltage conversion circuit 62, and a positive feedback circuit (PFB) 63.Details will be described later with reference to FIG. 3.

In addition to receiving the output signal VCO from the comparisoncircuit 51, the data storage unit 52 receives a WR signal indicating apixel signal writing operation and an RD signal indicating a pixelsignal reading operation from the vertical drive circuit 27, and a WORDsignal for controlling the read timing of the pixel 21 during a readoperation of the pixel signal from the vertical drive circuit 27.Furthermore, the time code generated by the time code generation unit 26is also supplied via the time code transfer unit 23.

The data storage unit 52 includes a latch control circuit 71 thatcontrols a write operation and a read operation for a time code on thebasis of the WR signal and the RD signal, and a latch storage unit 72that stores the time code.

In the time code writing operation, the latch control circuit 71 causesthe latch storage unit 72 to store the time code supplied from the timecode transfer unit 23 and updated every unit time while the Hi (High)output signal VCO is input from the comparison circuit 51.

Then, when the reference signal REF and the pixel signal SIG are thesame (voltage) and the output signal VCO supplied from the comparisoncircuit 51 is inverted to Lo (Low), writing (updating) of the suppliedtime code is stopped, and the time code stored last in the latch storageunit 72 is retained in the latch storage unit 72. The time code storedin the latch storage unit 72 represents the time when the pixel signalSIG and the reference signal REF are equal, and data indicating that thepixel signal SIG was the reference voltage at that time, i.e., adigitized light amount value.

After the sweep of the reference signal REF ends, and the time code isstored in the latch storage units 72 of all the pixels 21 in the pixelarray unit 22, the operation of the pixel 21 is changed from the writeoperation to the read operation.

In the time code read operation, the latch control circuit 71 outputsthe time code (digital pixel signal SIG) stored in the latch storageunit 72 to the time code transfer unit 23 when the pixel 21 has reachedits own read timing on the basis of the WORD signal that controls theread timing. The time code transfer unit 23 sequentially transfers thesupplied time code in the column direction (vertical direction) andsupplies it to the output unit 28.

In the following, in order to distinguish from the time code written inthe latch storage unit 72 in the time code write operation, thedigitized pixel data indicating that the pixel signal SIG was thereference voltage at that time, which is an inverted time code when theoutput signal VCO read from the latch storage unit 72 in the time coderead operation is inverted, is also referred to as AD converted pixeldata.

<First Configuration Example of the Comparison Circuit>

FIG. 3 is a circuit diagram illustrating a detailed configuration of thedifferential input circuit 61, the voltage conversion circuit 62, andthe positive feedback circuit 63 that constitute the comparison circuit51.

The differential input circuit 61 compares the pixel signal SIG outputfrom the pixel circuit 41 in the pixel 21 with the reference signal REFoutput from the DAC 25, and outputs a predetermined signal (current)when the pixel signal SIG is higher than the reference signal REF.

The differential input circuit 61 includes transistors 81 and 82 forminga differential pair, transistors 83 and 84 constituting a currentmirror, a transistor 85 as a constant current source for supplyingcurrent Icm corresponding to input bias current Vb, and a transistor 86for outputting output signal HVO of the differential input circuit 61.

The transistors 81, 82, and 85 are constituted by negative channel MOS(NMOS) transistors, and the transistors 83, 84, and 86 are constitutedby positive channel MOS (PMOS) transistors.

Of the transistors 81 and 82 forming the differential pair, thereference signal REF output from the DAC 25 is input to the gate of thetransistor 81, and the pixel signal SIG output from the pixel circuit 41in the pixel 21 is input to the gate of the transistor 82. The sourcesof the transistors 81 and 82 are connected to the drain of thetransistor 85, and the source of the transistor 85 is connected to apredetermined voltage VSS (VSS<VDD2<VDD1).

The drain of the transistor 81 is connected to the gates of thetransistors 83 and 84 constituting the current mirror circuit and thedrain of the transistor 83, and the drain of the transistor 82 isconnected to the drain of the transistor 84 and the gate of thetransistor 86. The sources of the transistors 83, 84, and 86 areconnected to a first power supply voltage VDD1.

The voltage conversion circuit 62 includes, for example, an NMOStransistor 91. The drain of the transistor 91 is connected to the drainof the transistor 86 of the differential input circuit 61, the source ofthe transistor 91 is connected to a predetermined connection point inthe positive feedback circuit 63, and the gate of the transistor 86 isconnected to bias voltage VBIAS.

The transistors 81 to 86 that constitute the differential input circuit61 are circuits that operate at a high voltage up to the first powersupply voltage VDD1, and the positive feedback circuit 63 is a circuitthat operates at a second power supply voltage VDD2 that is lower thanthe first power supply voltage VDD1. The voltage conversion circuit 62converts the output signal HVO input from the differential input circuit61 into a low voltage signal (conversion signal) LVI that allows thepositive feedback circuit 63 to operate, and supplies it to the positivefeedback circuit 63.

It is sufficient if the bias voltage VBIAS is a voltage that can beconverted into a voltage that does not destroy the transistors 101 to105 of the positive feedback circuit 63 operating at a constant voltage.For example, the bias voltage VBIAS can be the same voltage as thesecond power supply voltage VDD2 of the positive feedback circuit 63(VBIAS=VDD2).

The positive feedback circuit 63 outputs a comparison result signal thatis inverted when the pixel signal SIG is higher than the referencesignal REF on the basis of the conversion signal LVI obtained byconverting the output signal HVO from the differential input circuit 61into a signal corresponding to the second power supply voltage VDD2.Furthermore, the positive feedback circuit 63 increases the transitionspeed when the output signal VCO output as the comparison result signalis inverted.

The positive feedback circuit 63 includes seven transistors 101 to 107.Here, the transistors 101, 102, 104, and 106 are configured by PMOStransistors, and the transistors 103, 105, and 107 are configured byNMOS transistors.

The source of the transistor 91 which is the output terminal of thevoltage conversion circuit 62 is connected to the drains of thetransistors 102 and 103 and the gates of the transistors 104 and 105.The source of the transistor 101 is connected to the second power supplyvoltage VDD2, the drain of the transistor 101 is connected to the sourceof the transistor 102, and the gate of the transistor 102 is connectedto the drains of the transistors 104 and 105 that are also the outputterminals of the positive feedback circuit 63.

The sources of the transistors 103, 105, and 107 are connected to thepredetermined voltage VSS. An initialization signal INI is supplied tothe gates of the transistors 101 and 103. A control signal TERM, whichis a second input and is not the conversion signal LVI, which is a firstinput, is supplied to the gate of the transistor 106 and the gate of thetransistor 107.

The source of the transistor 106 is connected to the second power supplyvoltage VDD2, and the drain of the transistor 106 is connected to thesource of the transistor 104. The drain of the transistor 107 isconnected to the output terminal of the comparison circuit 51, and thesource of the transistor 107 is connected to the predetermined voltageVSS.

In the comparison circuit 51 configured as described above, when thecontrol signal TERM that is the second input is set to Hi, the outputsignal VCO can be set to Lo regardless of the state of the differentialinput circuit 61.

For example, when the voltage of the pixel signal SIG falls below thefinal voltage of the reference signal REF due to a higher brightnessthan expected (for example, a sun image reflected in the angle of viewof the imaging apparatus 1), the output signal VCO of the comparisoncircuit 51 becomes Hi and the comparison period ends, such that the datastorage unit 52 controlled by the output signal VCO cannot fix the valueand loses the AD conversion function.

In order to prevent such a situation from occurring, by inputting the Hipulse control signal TERM at the end of the sweep of the referencesignal REF, the output signal VCO that has not yet been inverted to Locan be forcibly inverted. Since the data storage unit 52 stores(latches) the time code immediately before the forcible inversion, in acase where the configuration of FIG. 3 is adopted, the ADC 42 eventuallyfunctions as an AD converter that clamps the output value with respectto luminance input at a certain level or more.

When the bias voltage VBIAS is controlled to Lo level, the transistor 91is shut off, and the initialization signal INI is set to Hi, the outputsignal VCO becomes Hi regardless of the state of the differential inputcircuit 61. Therefore, by combining the forced Hi output of the outputsignal VCO and the forced Lo output by the control signal TERM describedabove, the output signal VCO can be set to any value regardless of thestates of the differential input circuit 61 and the pixel circuit 41 andthe DAC 25, which are the preceding stage.

With this function, for example, it is possible to test a circuitsubsequent to the pixel 21 with only an electric signal input withoutdepending on an optical input to the imaging apparatus 1.

<Detailed Configuration Example of the Pixel Circuit>

A detailed configuration of the pixel circuit 41 will be described withreference to FIG. 4. FIG. 4 is a circuit diagram illustrating details ofthe pixel circuit 41 in addition to the differential input circuit 61 ofthe comparison circuit 51 illustrated in FIG. 3.

The pixel circuit 41 includes a photodiode (PD) 121 as a photoelectricconversion element, a discharge transistor 122, a transfer transistor123, a reset transistor 124, and an FD (floating diffusion layer) 125.

The discharge transistor 122 is used in a case where the exposure periodis adjusted. Specifically, when the discharge transistor 122 is turnedon when it is desired to start the exposure period at optimal timing,the charge accumulated in the photodiode 121 until then is discharged.Therefore, after the discharge transistor 122 is turned off, theexposure period starts.

The transfer transistor 123 transfers the charge generated by thephotodiode 121 to the FD 125. A reset transistor 124 resets the chargeheld in the FD 125. The FD 125 is connected to the gate of thetransistor 82 of the differential input circuit 61. Therefore, thetransistor 82 of the differential input circuit 61 also functions as anamplification transistor of the pixel circuit 41.

The source of the reset transistor 124 is connected to the gate of thetransistor 82 of the differential input circuit 61 and the FD 125, andthe drain of the reset transistor 124 is connected to the drain of thetransistor 82. Therefore, there is no fixed reset voltage for resettingthe charge of FD 125. This is because the reset voltage for resettingthe FD 125 can be arbitrarily set using the reference signal REF bycontrolling the circuit state of the differential input circuit 61, andthe fixed pattern noise of the circuit is stored in the FD 125 so thatits component can be cancelled by the CDS operation.

<Pixel Unit Timing Chart>

The operation of the pixel 21 illustrated in FIG. 4 will be describedwith reference to the timing chart of FIG. 5.

First, at time t1, the reference signal REF is set to reset voltageV_(rst) that resets the charge of the FD 125 from standby voltageV_(stb) up to then, and the charge of the FD 125 is reset by turning onthe reset transistor 124. Furthermore, at time t1, the initializationsignal INI supplied to the gates of the transistors 101 and 103 of thepositive feedback circuit 63 is set to Hi, and the positive feedbackcircuit 63 is set to the initial state.

At time t2, the reference signal REF is raised to predetermined voltageV_(u), and comparison between the reference signal REF and the pixelsignal SIG (sweep of the reference signal REF) is started. At this pointof time, because the reference signal REF is larger than the pixelsignal SIG, the output signal VCO is Hi.

At time t3 when it is judged that the reference signal REF and the pixelsignal SIG are the same, the output signal VCO is inverted (transitionedto Low). When the output signal VCO is inverted, the positive feedbackcircuit 63 speeds up the inversion of the output signal VCO as describedabove. Furthermore, the data storage unit 52 stores time data (N-bitDATA [1] to DATA [N]) at the point of time when the output signal VCO isinverted.

At time t4 when the signal write period ends and the signal read periodstarts, the voltage of the reference signal REF supplied to the gate ofthe transistor 81 of the comparison circuit 51 is reduced to the levelat which the transistor 81 is turned off (standby voltage V_(stb)).Therefore, the current consumption of the comparison circuit 51 duringthe signal read period is suppressed.

At time t5, the WORD signal for controlling the read timing becomes Hi,and N-bit latched time signals DATA [0] to DATA [N] are output from thelatch control circuit 71 of the data storage unit 52. The data acquiredhere is P-phase data at a reset level when correlated double sampling(CDS) processing is performed.

At time t6, the reference signal REF is raised to the predeterminedvoltage V_(u), the initialization signal INI supplied to the gates ofthe transistors 101 and 103 is set to Hi, and the positive feedbackcircuit 63 is set to the initial state again.

At time t7, the transfer transistor 123 of the pixel circuit 41 isturned on by a Hi transfer signal TX, and the charge generated by thephotodiode 121 is transferred to the FD 125.

After the initialization signal INI is returned to Low, the comparisonbetween the reference signal REF and the pixel signal SIG (sweep of thereference signal REF) is started. At this point of time, because thereference signal REF is larger than the pixel signal SIG, the outputsignal VCO is Hi.

Then, at time t8 when it is judged that the reference signal REF and thepixel signal SIG are the same, the output signal VCO is inverted(transitioned to Low). When the output signal VCO is inverted, thepositive feedback circuit 63 speeds up the inversion of the outputsignal VCO. Furthermore, the data storage unit 52 stores time data(N-bit DATA [1] to DATA [N]) at the point of time when the output signalVCO is inverted.

At time t9 when the signal write period ends and the signal read periodstarts, the voltage of the reference signal REF supplied to the gate ofthe transistor 81 of the comparison circuit 51 is reduced to the levelat which the transistor 81 is turned off (standby voltage V_(stb)).Therefore, the current consumption of the comparison circuit 51 duringthe signal read period is suppressed.

At time t10, the WORD signal for controlling the read timing becomes Hi,and N-bit latched time signals DATA [0] to DATA [N] are output from thelatch control circuit 71 of the data storage unit 52. The data acquiredhere is D-phase data of the signal level when CDS processing isperformed. Time t11 is the same state as time t1 described above inwhich the next 1V (one vertical scanning period) is driven.

By the drive of the pixel 21 described above, first, P-phase data (resetlevel) is acquired and then read, and next D-phase data (signal level)is acquired and read.

With the above operation, each pixel 21 of the pixel array unit 22 ofthe imaging apparatus 1 can perform a global shutter operation in whichall the pixels are reset simultaneously and all the pixels are exposedsimultaneously. Because all the pixels can be exposed and readsimultaneously, it is not necessary to provide a holding portion thatholds a charge until the charge is read that is usually provided in thepixel. Furthermore, the configuration of the pixel 21 does not require aselection transistor or the like for selecting a pixel that outputs thepixel signal SIG, which is necessary for a column parallel read typeimaging apparatus.

By the drive of the pixel 21 described with reference to FIG. 5, thedischarge transistor 122 is always controlled to be off. However, asindicated by the broken lines in FIG. 5, at a desired time, a dischargesignal OFG is set to Hi and the discharge transistor 122 is once turnedon and then turned off to set an arbitrary exposure period.

<Regarding Noise>

Incidentally, the noise level of the imaging apparatus 1 (FIG. 1) isdefined by thermal noise, 1/f noise, and quantization noise. In order toreduce the thermal noise, it is conceivable to improve the gm of thecircuit, but the current consumed by the analog circuit is increased,and the power may be increased.

Furthermore, the 1/f noise is also sensitive to current, but it ismainly determined by the area and the process, and measures for thesecan increase costs. The quantization noise is uniquely determined by theresolution of the ADC 42, but at low illumination, it is defined by therandom noise (thermal noise or 1/f noise) of the image sensor itself andthe quantization noise of the ADC 42, and the thermal noise and the 1/fnoise depend on the amount of current consumed by the analog circuit.

Thus, the imaging apparatus 1 that can achieve low power at highillumination and low noise at low illumination by adaptively variablyadjusting the current consumed by the analog circuit from the ADconverted output signal (output signal from ADC 42) will be furtherdescribed below.

In the following description, noise will be illustrated and described asfollows. As illustrated in FIG. 6, a predetermined circuit 301 is acircuit including noise. Noise is generated from a resistor element, acapacitor element, a transistor element, or the like in the circuit 301.It is assumed that external control for reducing the noise is performedon the circuit 301 including an element that may generate the noise.

In this case, as illustrated in FIG. 7, the following explanation isgiven by describing that the noise is equivalently input-referred, apredetermined amount of noise is given by input, and the circuit 302itself is noiseless. In the circuit diagram illustrated in FIG. 7, thecircuit 302 is a circuit that does not generate noise. An adding unit303 is provided outside the circuit 302, and a predetermined amount ofnoise is input to the adding unit 303. Since the adding unit 303 isconnected to the circuit 302, as a result, noise is supplied to thecircuit 302.

Referring to the circuit 301 illustrated in FIG. 6 again, for example,when the current flowing through the transistor element included in thecircuit 301 is changed, the amount of noise is also changed. In otherwords, the amount of noise can be controlled by controlling the currentflowing through the transistor element. Therefore, as illustrated inFIG. 8, it is conceived to control the current flowing through thetransistor element in a circuit 301′ (depicted with a prime fordistinction from the circuit 301 illustrated in FIG. 6) to control thenoise of the circuit 301′.

This can be represented by the noiseless circuit 302 illustrated in FIG.7 as illustrated in FIG. 9. That is, referring to FIG. 9, the noise ofthe circuit 302′ can be controlled by controlling the amount of noiseinput to the noiseless circuit 302′ (the amount of noise input to theadding unit 303).

As described above, in the imaging apparatus 1 noise such as thermalnoise, 1/f noise, and quantization noise occurs. The ADC 42 included inthe imaging apparatus 1 includes, for example, a plurality of transistorelements as illustrated in FIG. 3. A further description will be givenregarding the imaging apparatus 1 that controls the amount of noisegenerated in the ADC 42 by controlling the current flowing through thesetransistor elements and performs imaging with improved image quality.

<Configuration of the Imaging Apparatus that Performs Noise Control>

FIG. 10 is a diagram illustrating the configuration of an imagingapparatus that performs noise control, and particularly theconfiguration of the ADC 42 and peripheral circuits that include aconfiguration that controls the amount of noise generated in the ADC 42.In order to control the amount of noise generated in the ADC 42, ajudgement unit 401 that performs judgement described later on the basisof the output from the ADC 42 is provided.

As a result of judgement by the judgement unit 401, the amount of noisesupplied to the ADC 42 is controlled. As will be described later, theamount of noise is controlled by controlling the current flowing througha predetermined transistor element in the ADC 42. The judgement unit 401functions as a control unit that controls the current in the ADC 42.

As output from the ADC 42, reset digital data and signal digital dataare output. The difference between the reset digital data and the signaldigital data is calculated by the adding unit 402, and a signal ofcharges accumulated in (the photodiode 121 in) the pixel circuit 41 isgenerated and output as an output signal.

The output signal is also input to the judgement unit 401. As will bedescribed in detail later, the judgement unit 401 judges the nature of acaptured image, for example, whether it is high illuminance or lowilluminance, and as a result of the judgement, controls the amount ofnoise.

FIG. 11 is a diagram illustrating a configuration example of thejudgement unit 401. The judgement unit 401 includes a judgement valuecalculation unit 431, a comparison unit 432, a control table referenceunit 433, and a selection unit 434.

The pixel signal output from the ADC 42 is supplied to the judgementvalue calculation unit 431 of the judgement unit 401. The supplied pixelsignal may be a pixel value of the entire pixel area, a pixel value forone pixel, a pixel value representing a pixel including one or morepixels, and the like.

A pixel including one or more pixels may be, for example, a pixelarranged in a predetermined region of the pixel array unit or an imageplane phase difference pixel. Furthermore, such a pixel can be arepresentative pixel of pixels in a region around the pixel, and asignal from a pixel that is the representative pixel may be read beforea pixel that is not the representative pixel. Then, judgement can beperformed by the judgement unit 401 using a signal read from therepresentative pixel.

The unit of the pixel signal input to the judgement value calculationunit 431 can be matched with the unit to be controlled. For example, ina case where the control is performed in units of one pixel, the pixelsignal is supplied in units of one pixel.

That is, the accuracy with which the judgement unit 401 performs thejudgement can be the entire pixel area, the pixel unit, or the pluralityof pixel units.

The unit of the pixel signal input to the judgement value calculationunit 431 may be every pixel, every column, every pixel block including apredetermined number of pixels, all pixels, and the like.

Furthermore, control timing (timing for judgement), for example, timingwhen the pixel signal is input to the judgement value calculation unit431, timing for judgement by the judgement unit 401, and the like, maybe constant (per frame) or may be per a predetermined number of frames.

Note that the timing at which the judgement unit 401 performs thejudgement and the timing at which the current value and the like arecontrolled using the result of the judgement can be different asdescribed later. Here, the timing for performing the judgement isdescribed as the timing for control, and the description will becontinued.

Furthermore, in a case where one image is formed of a plurality offrames (subframes), control may be performed for each subframe, orcontrol may be performed in a predetermined subframe of the subframes.

For example, in a case where one subframe is generated using foursubframes, control may be performed for each subframe, or control may beperformed for a predetermined subframe of the four subframes, e.g., thefirst subframe (control using a value of the predetermined subframes isperformed for the other subframes).

The judgement value calculation unit 431 calculates an average value inthe screen, a representative value, a maximum value as to whether or notthe image is saturated, and the like, using the input pixel signal. Allof these may be calculated, or at least one of them may be calculated.

Note that the judgement value calculated by the judgement valuecalculation unit 431 may be calculated using a pixel signal that hasbeen subjected to processing such as defect correction in advance.

The judgement value from the judgement value calculation unit 431 issupplied to the comparison unit 432. A judgement threshold value is alsosupplied to the comparison unit 432. The judgement threshold value canbe configured to be supplied from the outside of the judgement unit 401,or can be configured to be held or generated by the comparison unit 432.The judgement threshold value may be a fixed value or may be a variablevalue that varies with a predetermined condition.

The comparison unit 432 compares the judgement value from the judgementvalue calculation unit 431 with the judgement threshold value, andsupplies a result of the comparison to the control table reference unit433. The control table reference unit 433 refers to a control signal fornoise control of the analog circuit, for example, a current value table.The table is a table in which, for example, the comparison result andthe current value are associated with each other.

The table may be held in the control table reference unit 433 or may beheld outside the control table reference unit 433.

The selection unit 434 is supplied with a reference value (for example,a current value), a forcible control value, and a mode selection signalfrom the control table reference unit 433. In response to the modeselection signal, the selection unit 434 judges whether or not toperform forcible control, and as a result of the judgement, selectseither the reference value or the forcible control value from thecontrol table reference unit 433, and supplies the result of theselection to each analog circuit, e.g., the ADC 42.

<First Configuration for Controlling the Current of the DifferentialInput Circuit>

FIG. 12 illustrates a configuration example of the ADC 42 and itsperipheral units in a case where the current flowing through thetransistor elements in the ADC 42 is controlled according to a result ofthe judgement from the judgement unit 401. FIG. 12 illustrates only thedifferential input circuit 61 in the ADC 42. A bias circuit 501 thatcontrols current Icm flowing through the transistor 85 of thedifferential input circuit 61 is connected to the gate of the transistor85.

The judgement result from the judgement unit 401 is supplied to the biascircuit 501. The bias circuit 501 includes a plurality of transistors511 and a current source 512. The bias circuit 501 is configured to becapable of changing the current value of the connected differentialinput circuit 61 by changing the number used from a plurality oftransistors constituting the transistor 511.

In a case where the current flowing through the bias circuit 501 iscurrent Ipixbias, channel length L of the transistor 511 is fixed,channel width W (bias W size) is Wpixbias, and the pixel current sourceW size is Wcmbias, the current Icm flowing through the transistor 85 isIcm=Ipixbias×(Wcmbias/Wpixbias).

That is, control is possible using the characteristic that the currentdensity per unit W is constant. Even if this current value is on theorder of one digit [nA] on the differential input circuit 61 side, theoperation is possible because of the configuration including thepositive feedback circuit 63 in the subsequent stage (PositiveFeedBackconfiguration).

In this way, by controlling the current flowing through the transistor(here, the transistor 85) in the differential input circuit 61, noisegenerated by the transistor 85 (the entire circuit including thetransistor 85) can be controlled.

For example, in a case where a bright image (high illuminance image) iscaptured, even if the noise is large, it is considered that theinfluence of the noise on the image quality is small. Furthermore, in acase where a dark image (low illuminance image) is captured, if thenoise is large, it is considered that the influence of the noise on theimage quality is large.

Furthermore, the noise also depends on the current value flowing throughthe transistor, and the noise tends to decrease as the current valueincreases.

For these reasons, when the judgement unit 401 can judge that an imagewith high illuminance is being captured, a judgement value that controlsthe current value of (the transistor 85 in) the differential inputcircuit 61 to be low is output to the bias circuit 501, and the biascircuit 501 performs control to reduce the current value in thedifferential input circuit 61. For this reason, when an image with ahigh illuminance is captured, a reduction in power can be achieved.

Furthermore, when the judgement unit 401 can judge that a lowilluminance image is being captured, a judgement value for controllingthe current value of (the transistor 85 in) the differential inputcircuit 61 is output to the bias circuit 501, and the bias circuit 501performs control to increase the current value in the differential inputcircuit 61. For this reason, noise can be reduced when an image with lowilluminance is captured.

<Second Configuration for Controlling the Current of the DifferentialInput Circuit>

FIG. 13 illustrates a second configuration example of the ADC 42 and itsperipheral units in a case where the current flowing through thetransistor elements in the ADC 42 is controlled according to a result ofthe judgement from the judgement unit 401. FIG. 13 illustrates only thedifferential input circuit 61 in the ADC 42. A DAC 25 that controls thereference signal REF supplied to the transistor 81 of the differentialinput circuit 61 is connected to the gate of the transistor 81.

As described above, the DAC 25 generates the reference signal (referencevoltage signal) REF, which is a slope signal whose level (voltage)monotonously decreases with time, and supplies it to each pixel 21.

The determination result from the judgement unit 401 is supplied to theDAC 25. The DAC 25 includes a resistor 551 and a current source 552. Inthe DAC 25, for example, the current source 552 includes a plurality ofcurrent sources, and the current value from the current source 552 iscontrolled by individually controlling on and off of the plurality ofcurrent sources.

The DAC 25 is configured such that the ground (GND) is a referencepotential, and the waveform of the DAC (the waveform of the referencesignal REF) is determined by IR drop of the current flowing through theresistor 551. In general, it is known that in a case where the currentis large, the current shot noise increases and the noise of the DAC 25deteriorates. In consideration of the voltage range of the FD 125 (FIG.4), for example, in a case where the signal amount is small, or thelike, the current of the DAC waveform is uniformly reduced asillustrated in FIG. 14.

In FIG. 14, the solid line indicates the waveform of the referencesignal REF during normal time, and the dotted line indicates thewaveform of the reference signal REF at a time when the current isuniformly reduced. Thus, by giving an offset to the reference signalREF, it is possible to reduce the noise generated in the DAC 25.

Although indicated here as DC, for example, it may be changed togetherwith the offset in accordance with the gain (gradient of the slope).Furthermore, as indicated by the dotted line in FIG. 14, since the DCvalue of the initial voltage of the FD 125 can also be reduced, the darkcurrent of the FD 125 can be suppressed, and the shot noise due to thedark current of the FD 125 can also be suppressed. Therefore, the randomnoise can be further reduced.

That is, in the case of a low luminance signal (when the signal level islow), control is performed to reduce dark current shot noise by reducingthe current value and setting the initial voltage of the FD 125 of thepixel low. On the other hand, in the case of a high luminance signal(when the signal level is high), control is performed such that thecurrent is increased and the voltage of the FD 125 is increased so thata high luminance signal can be obtained.

At this time, although there is a possibility that the dark current shotnoise increases, it is not noticeable because of high luminance.Furthermore, since one DAC 25 is provided for all the pixels, it doesnot consume as much power as the differential input circuit 61.Therefore, reducing the current of the differential input circuit 61results in lower power. For example, in a case where the pixel is 10Mpix, the effect can be obtained at 10M magnification.

<Third Configuration for Controlling the Current of the DifferentialInput Circuit>

The first configuration for controlling the current of the differentialinput circuit illustrated in FIG. 12 and the second configuration forcontrolling the current of the differential input circuit illustrated inFIG. 13 may be combined. FIG. 15 illustrates a configuration example ofthe ADC 42 and peripheral units thereof, in which the firstconfiguration and the second configuration are combined.

In the ADC 42 illustrated in FIG. 15, the bias circuit 501 that controlsa current flowing through the transistor 85 of the differential inputcircuit 61 is connected to the gate of the transistor 85. Furthermore,the DAC 25 that controls the reference signal REF supplied to thetransistor 81 of the differential input circuit 61 is connected to thegate of the transistor 81.

The judgement result from the judgement unit 401 are supplied to thebias circuit 501 and the DAC 25. The control performed by the biascircuit 501 and the DAC 25 is similar to the case described above.

That is, in a case where the judgement unit 401 judges that the signalvalue is a low luminance signal (signal level is low) that should beresistant to noise, the bias circuit 501 feeds back the current value tothe analog circuit (such as the ADC 42), and it works in the directionthat the noise is reduced. In the case of the differential input circuit61, control for increasing the current value of the current Icm flowingin the differential input circuit 61 is performed, and control forreducing the thermal noise generated by the circuit is performed.

Conversely, the DAC 25 performs control to reduce the dark current shotnoise by reducing the current value and setting the initial voltage ofthe FD 125 of the pixel low.

When the illuminance is high, the bias circuit 501 performs control forreducing the current Icm in the differential input circuit 61. At thistime, although the noise is increased, the differential input circuit 61can be reduced in power consumption. In contrast to the bias circuit501, the DAC 25 performs control to increase the current and increasethe voltage of the FD 125 so that a signal with high illuminance can beobtained.

Even with such a configuration, it is possible to control the currentflowing through the differential input circuit 61 and to control thenoise. Furthermore, by individually controlling the current flowingthrough the plurality of transistors in the differential input circuit61, the noise can be controlled more appropriately.

<Fourth Configuration for Controlling the Current of the DifferentialInput Circuit>

As described above, according to the first to third configurations ofthe differential input circuit, the noise can be suppressed. Forexample, as indicated by the dotted lines in FIG. 14 and as thedescription is added, according to the present technology, since the DCvalue of the initial voltage of the FD 125 can also be reduced, the darkcurrent of the FD 125 can be suppressed, and the shot noise due to thedark current of the FD 125 can also be suppressed. Therefore, the randomnoise can be further reduced.

That is, in the case of a low luminance signal (when the signal level islow), control is performed to reduce dark current shot noise by reducingthe current value and setting the initial voltage of the FD 125 of thepixel low. On the other hand, in the case of a high luminance signal(when the signal level is high), control is performed such that thecurrent is increased and the voltage of the FD 125 is increased so thata high luminance signal can be obtained.

By the way, as illustrated in FIG. 16, at time t11, in a case where theinitial voltage of the FD 125 is set to a low voltage (high potential),i.e., in a case where the reset voltage V_(rst) for resetting the chargeof the FD 125 is set to a low voltage (high potential), even if thetransfer gate (TG in the figure) is opened at time t12, the chargeremaining in the FD 125 does not flow back to the PD 121 side.

However, as illustrated in FIG. 17, at time t21, in a case where theinitial voltage of the FD 125 is set to a high voltage (low potential),i.e., in a case where the reset voltage V_(rst) for resetting the chargeof the FD 125 is set to a high voltage (low potential), when thetransfer gate (TG in the figure) is opened at time t22, there is apossibility that the charge remaining in the FD 125 flows back to the PD121 side.

As described above, according to the first to third configurations ofthe differential input circuit, control is performed to set the initialvoltage of the FD 125 of the pixel low, so that the dark current shotnoise can be reduced. When such control is performed, the situationdescribed with reference to FIG. 17 occurs, and there is a possibilitythat the charge remaining in the FD 125 flows back to the PD 121 side.

Therefore, a description will be given of a fourth configuration forcontrolling the current of the differential input circuit for performingcontrol so as to reduce the dark current shot noise and prevent thecharge remaining in the FD 125 from flowing back to the PD 121 side.

In the fourth configuration that controls the current of thedifferential input circuit, in order to suppress the dark current of theFD 125, the initial voltage of the FD 125 is reduced and in order tocreate a situation where transfer is possible and no backflow charge isgenerated, control of temporarily increasing the voltage of the FD 125during transfer (control for temporarily reducing the potential) isperformed.

FIG. 18 illustrates a configuration example (fourth configuration) ofthe ADC 42 and its peripheral units in a case where the current flowingthrough the transistor element in the ADC 42 is controlled according toa result of the judgement from the judgement unit 401. FIG. 18illustrates the differential input circuit 61 and the pixel circuit 41in the ADC 42.

A bias circuit 531 for controlling the current Icm flowing through thetransistor 85 of the differential input circuit 61 is connected to thegate of the transistor 85. The bias circuit 531 has a configuration inwhich a switch 541 and a switch 542 are added to the configuration ofthe bias circuit 501 (FIG. 12).

That is, the bias circuit 531 is configured to be supplied with thejudgement result from the judgement unit 401. Furthermore, the biascircuit 531 includes a plurality of transistors 511 and a current source512. The bias circuit 531 is configured such that the current value ofthe connected differential input circuit 61 can be varied by changingthe number of the plurality of transistors used constituting thetransistors 511.

Furthermore, the bias circuit 531 includes the switch 541 and the switch542. When one of the switch 541 and the switch 542 is opened, the otheris controlled to be closed.

Specifically, at the timing when the transfer gate TX is turned on, theswitch 541 is opened and the switch 542 is closed. Furthermore, at timesother than the timing when the transfer gate TX is turned on, the switch541 is closed and the switch 542 is opened.

The timing when the transfer gate TX is turned on may be the same timingas when the transfer gate TX is turned on, or may be timing just beforethe transfer gate TX is turned on.

With such control, when the transfer gate TX is turned on and transferof the charge from the FD 125 is started, the switch 541 is opened andthe switch 542 is closed, so that the gate of the transistor 85 is in agrounded state. When the gate of the transistor 85 is in a groundedstate, the potential of the drain of the transistor 85 is in a raisedstate.

Since the drain of the transistor 85 is connected to the source side ofthe transistor 82, as a result, the potential of the source of thetransistor 82 is in a raised state.

The transistor 82 of the differential input circuit 61 functions as anamplification transistor. When the parasitic capacitance of theamplification transistor is parasitic capacitance 551, when the sourceside of the transistor 85 becomes a high potential, the potential of theparasitic capacitance 551 of the amplification transistor rises.

Since the FD 125 is connected to the amplification transistor(transistor 82), when the potential of the parasitic capacitance 551increases, the potential of the FD 125 increases eventually.

As described above, when the transfer gate TX is turned on and transferof the charge from the FD 125 is started, by opening the switch 541 andclosing the switch 542, the voltage of the FD 125 can be boosted.

Even in the state of the time t21 illustrated in FIG. 17, by boostingthe FD 125, the state of the time t11 temporarily illustrated in FIG. 16is provided, and the charge remaining in the FD 125 can be preventedfrom flowing back to the PD 121 side.

Furthermore, by opening the switch 541 and closing the switch 542, thevoltage of the FD 125 is temporarily boosted, and then the switch 541 isclosed and the switch 542 is opened, it is possible to provide the statein which the bias circuit 531 supplies input bias current Vb to thetransistor 85. Therefore, as described above, it is possible to switchto a state where the dark current of the FD 125 can be suppressed, andthe shot noise due to the dark current of the FD 125 can be suppressed.

The operation of the pixel 21 illustrated in FIG. 18 will be describedwith reference to the timing chart of FIG. 19. The timing chartillustrated in FIG. 19 is a timing chart obtained by adding the controlpulse bias for controlling whether or not to supply the input biascurrent Vb from the bias circuit 53 and the voltage value of the FD 125to the timing chart illustrated in FIG. 5. Therefore, the description isomitted regarding what is described with reference to the timing chartillustrated in FIG. 5.

The control pulse bias is a pulse for controlling opening/closing of theswitch 541 and the switch 542. Here, it is assumed that when the controlpulse bias is off, the switch 541 is opened and the switch 542 isclosed. Therefore, in a case where the control pulse bias is off, thebias circuit 531 is in a grounded state, and the bias current Vb is in astate of not being supplied to the transistor 85.

Furthermore, when the control pulse bias is on, the switch 541 is closedand the switch 542 is opened. Therefore, in a case where the controlpulse bias is on, the bias circuit 531 is in a state of being connectedto the transistor 511, and the bias current Vb is in a state of beingsupplied to the transistor 85.

Therefore, when the control pulse bias is switched from on to off, thevalue of the input bias current Vb from the bias circuit 53 is switchedfrom a predetermined current value (for example, current Ipixbias) tozero (ground).

At time t7, the transfer transistor 123 of the pixel circuit 41 isturned on by a Hi transfer signal TX, and the charge generated by thephotodiode 121 is transferred to the FD 125. At time t6 before time t7,the switch 541 is opened and the switch 542 is closed by supplying anoff control pulse bias to the switch 541 and the switch 542.

Therefore, at time t7, the value of the input bias current Vb from thebias circuit 53 is switched from a predetermined current value (forexample, current Ipixbias) to zero (ground).

At time t6, when the value of the input bias current Vb from the biascircuit 53 is zero, the voltage value of the FD 125 is graduallyincreased.

Note that, here, a description is given of a case by way of examplewhere the timing at which the control pulse bias is turned off beforethe timing at which the transfer signal TX becomes Hi (the timing atwhich the value of the input bias current Vb from the bias circuit 531is set to zero, i.e., the timing at which the opening/closing of theswitches 541 and 542 is controlled) is set. However, the timing when thetransfer signal TX becomes Hi and the timing when the control pulse biasis turned off may be substantially the same (time t7).

At a point of time when the transfer signal TX returns to low (almostsimultaneously or after the transfer signal TX returns low), the valueof the input bias current Vb from the bias circuit 53 returns to apredetermined current value (for example, current Ipixbias). That is, inthis case, when the control pulse bias is turned back on, the switch 541is closed and the switch 542 is opened.

When the input bias current Vb from the bias circuit 53 is in a state ofbeing supplied to the differential input circuit 61, the voltage of theFD 125 is stepped down.

In this way, the voltage of the FD 125 is once boosted at the start oftransfer, so that the charge remaining in the FD 125 can be preventedfrom flowing back to the PD 121 side. Furthermore, when the voltage ofthe FD 125 is once boosted and then returned to its original state, andthe transfer of the charge from the FD 125 is performed in a state wherethe voltage has been returned to the original state, transfer thatsuppresses the generation of the dark current in the FD 125 can beperformed.

Note that a description is given of the case as an example where thebias circuit 531 illustrated in FIG. 18 includes the switch 541 and theswitch 542, but the bias circuit 531 may include one switch. In otherwords, the bias circuit 531 that performs the control described abovecan be provided as long as it includes one switch connected to theground side at the start of transfer and connected to the transistor 511at other times than the start of transfer, and such a configuration isalso within the scope of the present technology.

<Fifth Configuration for Controlling the Current of the DifferentialInput Circuit>

FIG. 20 illustrates a configuration example (fifth configuration) of theADC 42 and its peripheral units in a case where the current flowingthrough the transistor element in the ADC 42 is controlled according toa result of the judgement from the judgement unit 401. FIG. 20illustrates the differential input circuit 61 and the pixel circuit 41in the ADC 42.

In the configuration illustrated in FIG. 20, similar to FIG. 18, thebias circuit 571 that controls the current Icm flowing through thetransistor 85 of the differential input circuit 61 is connected to thegate of the transistor 85. This bias circuit 571 has a configuration inwhich a transistor 581 constituting a source follower circuit and avariable current source 582 are added to the configuration of the biascircuit 531 (FIG. 18), and a transistor 583 for adjusting the operatingpoint of the voltage is added.

The added transistor 581 and transistor 583 are, similar to thetransistor 511, each include a plurality of transistors.

For example, in the bias circuit 531 illustrated in FIG. 18, the drivecapability of the bias circuit 531 is determined by a transistorconnected to the photodiode 121 constituting the pixel 21.

When the number of pixels to which the circuits are connected increases,i.e., when the number of pixels 21 in the pixel array unit 22 (FIG. 1)increases, the number of bias circuits 531 connected to the pixels 21also increases.

When the number of pixels 21 increases in this way, it can be difficultto activate the bias circuit 531 within a specified time and flow thecurrent to all the pixels 21 in the pixel array unit 22 (to flow thecurrent within the limited ADC time).

Therefore, the configuration of the bias circuit 571 as illustrated inFIG. 20 is adopted so that the bias circuit 571 can be activated withina specified time even when the number of pixels 21 is increased.

The bias circuit 571 illustrated in FIG. 20 includes the source followercircuit including the transistor 581. The source follower circuit isused as a buffer, and a voltage once buffered in the buffer isconfigured to be supplied to the transistor 85. Therefore, by using thebuffered voltage, the bias circuit 571 can be activated within aspecified time.

The operation of the pixel 21 including the bias circuit 571 illustratedin FIG. 20 is performed according to the timing chart illustrated inFIG. 19. Since the description with reference to the timing chartillustrated in FIG. 19 has already been made, the description is omittedhere.

An arrangement example of the bias circuit 571 will be described withreference to FIGS. 21 and 22.

FIG. 21 is a diagram illustrating an example of an arrangement positionof the bias circuit 571 with respect to the pixel array unit 22. Here,the bias circuit 571 is described separately with respect to a switchcircuit 571 a and a bias circuit 571 b.

The switch circuit 571 a is a circuit including the switch 541 and theswitch 542, and the bias circuit 571 b is a circuit including thetransistor 511, the current source 512, the transistor 581, the variablecurrent source 582, and the transistor 583.

In the arrangement example illustrated in FIG. 21, the bias circuit 571is provided on one of the four sides of the pixel array unit 22, theswitch circuit 571 a is provided on the pixel array unit 22 side, andthe pixel array unit 22 (each pixel 21) is arranged to be connected tothe bias circuit 571 b across the switch circuit 571 a.

In the arrangement example illustrated in FIG. 22, bias circuits 571-1to 571-4 are provided on four of the four sides of the pixel array unit22, respectively. As in the arrangement example illustrated in FIG. 21,regarding the bias circuits 571 provided on the respective sides of thepixel array unit 22, switch circuits 571 a-1 to 571 a-4 are provided onthe pixel array unit 22 side, and the pixel array unit 22 (each pixel21) is arranged to be connected to bias circuits 571 b-1 to 571 b-4across the switch circuits 571 a-1 to 571 a-4.

In the arrangement example illustrated in FIG. 21, the bias circuit 571is illustrated to be provided on one of the four sides of the pixelarray unit 22, and in the arrangement example illustrated in FIG. 22,the bias circuits 571 are illustrated to be provided on the four of thefour sides of the pixel array unit 22. Although not illustrated, thebias circuit 571 can also be arranged to be provided on two of the foursides of the pixel array unit 22, or the bias circuit 571 can also bearranged to be provided on three of the four sides of the pixel arrayunit 22.

Which of the four sides of the pixel array unit 22 is provided with thebias circuit 571 is a design matter that can be appropriately changeddepending on layout constraints.

In a case where the bias circuit 571 is arranged on the four sides ofthe pixel array unit 22 as in the arrangement example illustrated inFIG. 22, the bias circuits 571 are arranged to be created as transistorshaving the same characteristics around the pixel array unit 22 and thebias current (voltage) can be supplied from the periphery. With sucharrangement, the characteristic difference between the sensors(characteristic difference between the pixels 21) can be reduced ascompared with a case where the bias circuit 571 is arranged on one sideof the pixel array unit 22 as in the arrangement example illustrated inFIG. 21.

In the arrangement examples illustrated in FIGS. 21 and 22, the biascircuit 571 has been described as an example. However, the arrangementexample illustrated in FIG. 21 or FIG. 22 can also be applied to thebias circuit 531 illustrated in FIG. 18.

<Sixth Configuration for Controlling the Current of the DifferentialInput Circuit>

FIG. 23 illustrates a configuration example (sixth configuration) of theADC 42 and its peripheral units in a case where the current flowingthrough the transistor element in the ADC 42 is controlled according toa result of the judgement from the judgement unit 401. FIG. 23illustrates the differential input circuit 61 and the pixel circuit 41in the ADC 42.

The configuration of the pixel circuit 41 illustrated in FIG. 23 is aconfiguration in which a wiring 611 is disposed in the vicinity of theFD 125 and the FD 125 and the wiring 611 are coupled as a configurationfor once boosting the voltage of the FD 125 at the start of transfer.

A bias circuit, for example, the bias circuit 501 illustrated in FIG.12, is connected to the differential input circuit 61, and the biascurrent Vb is configured to be supplied on the basis of the result ofjudgement of the judgement unit 401.

The wiring 611 is a metal wiring and is configured such that a voltageis applied at the start of transfer. For example, a voltage source canbe configured to be connected to the wiring 611, and the voltage sourcecan be controlled by the judgement unit 401 so as to apply a voltagehaving a predetermined voltage value to the wiring 611 at the time oftransfer.

When a voltage is applied to the wiring 611, the voltage of the coupledFD 125 is boosted. When a voltage is applied to the wiring 611, thepotential of the parasitic capacitance 612 increases, and the potentialof the FD 125 also increases.

The operation of the pixel 21 illustrated in FIG. 23 will be describedwith reference to the timing chart of FIG. 24. The timing chartillustrated in FIG. 24 is similar to the timing chart illustrated inFIG. 19, but the control pulse (control pulse bias) for applying avoltage to the wiring 611 is different. A description of the portionsdescribed with reference to the timing chart illustrated in FIG. 19 isomitted.

At time t7, the transfer transistor 123 of the pixel circuit 41 isturned on by a Hi transfer signal TX, and the charge generated by thephotodiode 121 is transferred to the FD 125. At time t6 prior to timet7, in order to apply a voltage to the wiring 611, an ON control pulsebias is output to a voltage source, which is not illustrated. Therefore,the voltage is applied to the wiring 611, and the voltage value of theFD 125 is boosted.

Note that, here, a description is given of a case by way of examplewhere the timing at which the control pulse bias is turned on before thetiming at which the transfer signal TX becomes Hi is set. However, thetiming when the transfer signal TX becomes Hi and the timing when thecontrol pulse bias is turned on may be substantially the same (time t7).

At the point of time when the transfer signal TX is returned to Low(almost simultaneously or after the transfer signal TX returns to Low),the control pulse bias is turned off, and the application of the voltageto the wiring 611 ends. When no voltage is applied to the wiring 611,the voltage of the FD 125 is lowered.

In this manner, when the voltage of the FD 125 is once boosted at thestart of transfer, the charge remaining in the FD 125 can be preventedfrom flowing back to the PD 121 side. Furthermore, when the voltage ofthe FD 125 is once boosted and then returned to its original state, andthe transfer of the charge from the FD 125 is performed in a state wherethe voltage has been returned to the original state, transfer thatsuppresses the generation of the dark current in the FD 125 can beperformed.

<Seventh Configuration for Controlling the Current of the DifferentialInput Circuit>

FIG. 25 illustrates a configuration example (seventh configuration) ofthe ADC 42 and its peripheral units in a case where the current flowingthrough the transistor element in the ADC 42 is controlled according toa result of the judgement from the judgement unit 401. FIG. 25illustrates the differential input circuit 61 and the pixel circuit 41in the ADC 42.

In the configuration of the differential input circuit 61 illustrated inFIG. 25, a transistor 631 is provided on the drain side of thetransistor 85 as a configuration for once boosting the voltage of the FD125 at the start of transfer. The transistor 631 functions as a switch,and is provided to connect or separate (disconnect) the transistor 85 inthe differential input circuit 61.

That is, when the transistor 631 is in a turned-on state as a switch,the transistor 85 is in a state of being connected in the differentialinput circuit 61, and the bias current Vb is in a state of beingsupplied from the bias circuit 501 to the transistor 85 and supplied tothe source side of the transistor 81 or the transistor 82.

On the other hand, when the transistor 631 is in a turned-off state as aswitch, the transistor 85 is in a state of being separated in thedifferential input circuit 61, and the bias current Vb is in a state ofbeing supplied from the bias circuit 501 to the transistor 85 but notsupplied to the source side of the transistor 81 or the transistor 82.

Furthermore, here, the transistor 631 is a transistor that includes anNMOS transistor, and when the control pulse bias is turned on, thevoltage is applied to the gate of the transistor 631, the transistor 631is in a turned-on state, and when the control pulse bias is turned off,no voltage is applied to the gate of the transistor 631, and thetransistor 631 is in a turned-off state.

In a case where the transistor 631 includes a PMOS transistor, theoperation is reversed. As the operation of the transistor 631, when thecontrol pulse bias is turned on, the voltage is applied to the gate ofthe transistor 631, the transistor 631 is in a turned-off state, andwhen the control pulse bias is turned off, no voltage is applied to thegate of the transistor 631, and the transistor 631 is in a turned-onstate.

Instead of the transistor 631, it may include a switch for turning onand off. Note that considering the formation of the transistor 631 inthe pixel 21, the formation as a transistor rather than as a switch hasan advantage that it can be manufactured in a process similar to theprocess of the formation of other transistors.

The operation of the pixel 21 including the transistor 631 illustratedin FIG. 25 is performed according to the timing chart illustrated inFIG. 19. Since the description with reference to the timing chartillustrated in FIG. 19 has already been made, a duplicate description isomitted.

At time t7, when the transfer transistor 123 of the pixel circuit 41 isturned on by the Hi transfer signal TX and the charge generated by thephotodiode 121 is started to be transferred to the FD 125 (before it isstarted), the control pulse bias is turned off, no voltage is applied tothe gate of the transistor 631, the transistor 631 is in a turned-offstate, the potential of the parasitic capacitance 551 increases, and, asa result, the voltage of the FD 125 is boosted.

Thereafter, at the point of time when the transfer signal TX is returnedto Low (at almost the same time or after the transfer signal TX returnsto Low), when the control pulse bias is turned back on, the voltage isapplied to the gate of the transistor 631, the transistor 631 is in aturned-on state, the potential of the parasitic capacitance 551 islowered, and, as a result, the voltage of the FD 125 is stepped down.

In this manner, when the voltage of the FD 125 is once boosted at thestart of transfer, the charge remaining in the FD 125 can be preventedfrom flowing back to the PD 121 side. Furthermore, after the voltage ofthe FD 125 is once boosted, the charge is transferred from the FD 125,and after that transfer, the voltage is returned to the original voltagesuch that the transfer that suppresses the generation of dark current inthe FD 125 can be performed.

Note that the first to seventh configurations for controlling thecurrent of the differential input circuit can be applied alone or incombination.

<Regarding Timing of Application of Control>

As described above, the noise in the ADC 42 is controlled on the basisof the result of the judgement of the judgement unit 401. The timing atwhich the result of the judgement of the judgement unit 401 is outputand the timing at which the result of the judgement applied will bedescribed with reference to FIG. 26.

The pixel 21 starts exposure at a predetermined timing. By the drive ofthe pixel 21 described with reference to FIG. 5, the dischargetransistor 122 is always controlled to be off. However, as indicated bythe broken lines in FIG. 5, at a desired time, the discharge signal OFGis set to Hi and the discharge transistor 122 is once turned on and thenturned off to set an arbitrary exposure period. For example, the startof exposure can be defined by a falling pulse of OFG (FIG. 5).

The exposure time is from the start of exposure to the falling time ofthe transfer signal TX (FIG. 5). In the case of one ADC 42 per pixel,the ratio is 1:1. However, when the FD 125 is shared by a plurality ofpixels and one ADC 42 is used, the exposure time can be individually set(pixel sharing will be described later).).

An RST (reset) period is provided during the exposure period, the FD 125is initialized, AutoZero of the comparison circuit 51 (FIG. 2) isperformed, and preparations for starting the processing in the ADC 42are performed. Thereafter, the positive feedback circuit (PSB) 63 isinitialized, and, at the same time, the initial voltage of the DAC 25 isset.

After the reset period, a P-phase acquisition period (hereinafter simplyreferred to as a P-phase, P-phase acquisition period, etc.), which is anA/D conversion period of the reset level of the pixel. The voltage ofthe DAC 25 is gradually lowered, and data is written to the latchstorage unit (FIG. 2). When the signal from the pixel circuit 41 inputto the differential input circuit 61 and the signal from the DAC 25 havethe same value (same voltage), the output from the comparison circuit 51is inverted, and writing data is written on the latch storage unit 72.

Note that, here, the case where the positive feedback circuit 63 isprovided is described as an example as a circuit for speeding up thereaction, but as long as a circuit can achieve a similar function(storage of latch data over a predetermined time), any other circuitsmay be used.

Data acquired in the P-phase acquisition period is output from the ADC42 in the P-phase output period.

After the P-phase output period, a D-phase acquisition period(hereinafter simply referred to as D-phase, D-phase acquisition period,etc.) that is an A/D conversion period of the signal level of the pixelis provided. In the D-phase acquisition period, the transfer transistor123 (FIG. 4) is turned on, and the signal of the photodiode 121 istransferred to the FD 125. The voltage of the DAC 25 is graduallylowered, and the time code from the time code transfer unit 23 issupplied to the latch control circuit 71 (FIG. 2).

When the signal from the pixel circuit 41 input to the differentialinput circuit 61 and the signal from the DAC 25 have the same value(same voltage), the output from the comparison circuit 51 is inverted,and the time code at that time is written in the latch storage unit 72.

By dropping the signal (slope) from the DAC 25 to the GND level (voltageat which the pixel current is turned off), the power consumed by the ADC42 in the pixel 21 is set to the zero state, and the standby state isset.

On the other hand, the data acquired in the D-phase acquisition periodis output from the ADC 42 in the D-phase output period.

A processing unit (not illustrated) that processes the signal from theADC 42 performs CDS of the P-phase data and the D-phase data, therebyremoving fixed pattern noise, FD 125 reset noise, and circuit resetnoise.

At this time, the finally remaining noise is thermal noise, 1/f noise,and random telegraph signal (RTS) noise determined by the value of thecurrent that the analog circuit flows during the operation. In order tocontrol these noises, the noise can be reduced by controlling thecurrent value in the circuit (ADC 42) according to the output signallevel as described above.

Therefore, as the timing for controlling the noise according to theoutput signal level, for example, there is timing as illustrated in FIG.26. Note that, here, the noise control by the bias circuit 501 will bedescribed as an example.

The signals of all the pixels may be read to calculate the average valueof the signals and calculate the amount of current flowing through apredetermined transistor in the ADC 42 from the average value.Furthermore, a part of the D-phase output may be read out, the luminancevalue thereof may be judged, and the current value (bias value) of thenext frame may be calculated.

In FIG. 26, in the D-phase output period, the current value Icm iscalculated by the judgement unit 401, and after the start of exposure ofthe next frame and before the reset period, the calculated current valueIcm is applied to the analog circuit, for example, the differentialinput circuit 61 in the ADC 42.

Note that, the current value Icm can be configured to be calculated inthe P-phase output period, and the current value Icm calculated in theD-phase acquisition period of the same frame can be applied. However, insuch a case, data to which different current values Icm are applied inthe P-phase and the D-phase in the same frame will be used, and in theCDS of the P-phase data and the D-phase data, there is a possibilitythat the noise cannot be removed properly.

Therefore, as described above, the current value Icm is calculated inthe D-phase output period, and after the start of exposure of the nextframe, before the reset period, i.e., in the P-phase acquisition periodand the D-phase acquisition period of the next frame, the calculatedcurrent value Icm is configured to be applied.

Note that, the current value Icm can be calculated in the P-phase outputperiod, and the calculated current value Icm can be configured to beapplied during the P-phase acquisition period and the D-phaseacquisition period of the next frame.

A description will be given of the calculation of the current value Icm.Here, a case where the maximum output value is 14 bits (taken from 0 to16383) will be described as an example. In a case where the output afterCDS is less than 4096 continues over 8 frames, the (captured) image tobe processed is determined to be dark, and the setting value of thecurrent value Icm for improving the noise on the low illuminance side isdriven to increase.

On the other hand, in a case where the output after CDS continues for 8frames with a value larger than 4096, it is considered that there aremany high illuminance signals, and it is determined to be a bright imagethat may acquire a shot noise dominant image and is driven to reduce thesetting of the current value Icm.

By providing hysteresis in this way, a mechanism that prevents thescreen from flickering near the threshold of 4096 may be provided. Notethat, although 8 frames were mentioned here as an example, it isneedless to say that the number of frames may be other than 8 frames.

<Sharing Pixel Structure>

In the embodiment described above, the comparison circuit 51 isconfigured such that one ADC 42 is arranged in one pixel 21, but can beconfigured such that a plurality of pixels 21 shares one ADC 42.

FIG. 27 is a circuit diagram illustrating a configuration example of thecomparison circuit 51 in the case of pixel sharing in which one ADC 42is shared by a plurality of pixels 21. FIG. 27 illustrates aconfiguration example of the comparison circuit 51 in a case where oneADC 42 is shared by four pixels 21: a pixel 21A, a pixel 21B, a pixel21C, and a pixel 21D.

In FIG. 27, the configurations of the differential input circuit 61, thevoltage conversion circuit 62, and the positive feedback circuit 63constituting the comparison circuit 51 are similar to the configurationillustrated in FIG. 2.

In FIG. 27, pixel circuits 41A to 41D are provided for the four pixels21A to 21D, and a photodiode 121 q, a discharge transistor 122 q, and atransfer transistor 123 q are individually provided for the pixelcircuits 41A to 41D. On the other hand, the reset transistor 124′ andthe FD 125′ are shared by the four pixels 21A to 21D.

Note that, in FIG. 27, the circuit configuration illustrated in FIG. 2is adopted as the circuit configuration of the comparison circuit 51,but other circuit configurations may be adopted.

In this way, the configuration illustrated in FIG. 12, 13, or 15 can beapplied to sharing pixels in which a plurality of pixels 21 shares oneADC 42 to control the current in the ADC 42 (noise of the ADC 42).

The configuration of the differential input circuit 61 in the case ofthe pixel configuration of four pixel sharing illustrated in FIG. 27 is,for example, the same as the configuration of the differential inputcircuit 61 in the case of the pixel configuration, which is not pixelsharing illustrated in FIG. 12. Thus, for example, similar to the caseillustrated in FIG. 12, the bias circuit 501 can be provided in thepixel configuration of four pixel sharing illustrated in FIG. 27, andthe bias circuit 501 can be configured to be connected to the gate ofthe transistor 85 in the differential input circuit 61.

With this configuration, as in the case described with reference to FIG.12, the current flowing through the transistor 85 can be controlled onthe basis of the judgement of the judgement unit 401 (for example,judgement of whether the illumination is high or low), and the noisegenerated in (the comparison circuit 51 including) the differentialinput circuit 61 can be controlled.

Furthermore, similar to the case illustrated in FIG. 13, the DAC 25 isprovided in the four pixel sharing pixel configuration illustrated inFIG. 27, and the DAC 25 can be configured to be connected to the gate ofthe transistor 81 in the differential input circuit 61.

With this configuration, as in the case described with reference to FIG.13, the reference signal REF supplied to the transistor 81 can becontrolled on the basis of the judgement of the judgement unit 401 (forexample, judgement of whether the illumination is high or low), and thenoise generated in (the comparison circuit 51 including) thedifferential input circuit 61 can be controlled.

Furthermore, similar to the case illustrated in FIG. 15, the biascircuit 501 and the DAC 25 can be provided in the four pixel sharingpixel configuration illustrated in FIG. 27, the bias circuit 501 can beconnected to the gate of the transistor 85 in the differential inputcircuit 61, and the DAC 25 can be configured to be connected to the gateof the transistor 81 in the differential input circuit 61.

With this configuration, as in the case described with reference to FIG.15, the current flowing through the transistor 85 can be controlled andthe reference signal REF supplied to the transistor 81 can be controlledon the basis of the judgement of the judgement unit 401 (for example,judgement of whether the illumination is high or low), and the noisegenerated in (the comparison circuit 51 including) the differentialinput circuit 61 can be controlled.

<Regarding Timing of Application of Control in Sharing Pixels>

The timing at which the result of judgement of the judgement unit 401 inthe sharing pixels is output and the timing at which the result of thejudgement is applied will be described with reference to FIG. 28.

In the sharing pixels, the processing performed by each pixel circuit 41is similar to the case described with reference to FIG. 26. That is,each pixel circuit 41 is provided with a reset period, a P-phaseacquisition period, a P-phase output period, a D-phase acquisitionperiod, and a D-phase output period after the start of exposure, andexecutes a corresponding process in each period.

Here, a case where exposure is started by turning on the dischargetransistor 122 (OFG) will be described as an example. In each pixelcircuit 41, the exposure period is from the fall of the dischargetransistor 122 provided in each pixel circuit 41 to the fall of thetransfer transistor 123.

By controlling the four pixels individually, it is possible to acquirefour global shutter images shifted by one pixel in terms of spatialresolution. By individually controlling the exposure times of these fourimages (not having the same exposure time), high dynamic range (HDR)imaging becomes possible.

For example, when the exposure time of the pixel circuit 41A is Ta, theexposure time of the pixel circuit 41B is Tb, the exposure time of thepixel circuit 41C is Tc, and the exposure time of the pixel circuit 41Dis Td such that Ta:Tb:Tc:Td=1:4:16:64, the dynamic range can beincreased 64 times in the exposure time ratio.

Even if an image is saturated at 64 times exposure, whiteout can beprevented when it is not saturated at 1 time exposure.

When such a drive is performed, in a case where it is dark as a wholewithout saturation at the shortest exposure time Ta, for example, whenit is a value of 64 LSB or less with 1 bit, in a case where acquisitionis made with the exposure time Td, output after CDS is likely to be 4096or less. In such a case, as in the case described with reference to FIG.26, for example, after reading out the exposure time Td having thelongest exposure time after eight consecutive frames, the current Icm inthe differential input circuit 61 or the current of the reference signalRef (generated by the DAC 25) supplied to the differential input circuit61 is controlled, and the generation of noise is suppressed.

Furthermore, in the case where only the exposure time Ta is used and thesetting accuracy cannot be obtained due to the influence of shot noiseor the like, control may be made such that signals of the exposure timeTb and Tc are used in combination to similarly judge whether, forexample, the average value at the exposure time Tb exceeds 256 and theaverage value at the exposure time Tc exceeds 1024, and the result isapplied to the exposure time Td after a certain frame.

Furthermore, the calculation may be performed with the exposure time Tdof a predetermined frame, and the calculated setting may be applied tothe exposure times Ta, Tb, Tc, Td of the next frame after thepredetermined frame. According to such control, it is possible tooptimize power consumption by applying only to long-time exposure Td inwhich a dark image that is most desired to avoid the influence of noiseis output while performing shooting by HDR.

Note that, here, the case where the output is performed four times inthe order of the P phase and the D phase has been described as anexample, but the present technology described above can be basicallysimilarly applied to reading in the order of the reverse D phase and theP phase, combined reading of the P phase and the D phase, or twicereading, 16 times reading, or the like, not four times reading.

Note that, here, four-pixel sharing has been described as an example,but the present technology can also be applied to, for example,two-pixel sharing or the like, other than four-pixel sharing.

<Multiple Substrate Configuration>

In the description heretofore, the imaging apparatus 1 has beendescribed as being formed on a single semiconductor substrate 11, butthe imaging apparatus 1 may be configured by creating circuits on aplurality of semiconductor substrates 11.

FIG. 29 is a conceptual diagram constituting the imaging apparatus 1 bystacking two semiconductor substrates 11: an upper substrate 11A and alower substrate 11C.

At least the pixel circuit 41 including the photodiode 121 is formed onthe upper substrate 11A. The lower substrate 11C is provided with atleast the data storage unit 52 for storing a time code and the time codetransfer unit 23. The upper substrate 11A and the lower substrate 11Care bonded by, for example, a metal bonding or the like, of Cu—Cu or thelike.

FIG. 30 illustrates a circuit configuration example formed on each ofthe upper substrate 11A and the lower substrate 11C. On the uppersubstrate 11A, the pixel circuit 41 and a circuit of the transistors 81,82, and 85 of the differential input circuit 61 of the ADC 42 areformed. On the lower substrate 11C, the circuit of the ADC 42 excludingthe transistors 81, 82, and 85 and the time code transfer unit 23 areformed.

The upper substrate 11A may be a pixel wafer made only of NMOS, and thelower substrate 11C may be a logic wafer on which circuits ahead of thePMOS included in the differential input circuit 61 are formed. Byconfiguring in this way, in response to the slow response of the PMOS ofthe differential input circuit 61, when the NOR threshold value of thelatter stage is exceeded, the feedback (positive feedback) to the PMOSto the constant voltage side is made to sharply perform reaction.

For this reason, the time of the through current is minimized, and atthe same time, a digital signal (Gray code) supplied from the outsidecan be accurately latched and stored. The latched data is output to anexternal processing unit and used for processing such as CDS.

<Multiple Substrate Configuration 2>

FIGS. 29 and 30 are an example in which the imaging apparatus 1 isconfigured by two semiconductor substrates 11, but may be configured bythree semiconductor substrates 11.

FIG. 31 illustrates a conceptual diagram constituting the imagingapparatus 1 by stacking three semiconductor substrates 11: an uppersubstrate 11A, an intermediate substrate 11B, and a lower substrate 11C.

On the upper substrate 11A, the pixel circuit 41 including thephotodiode 121 and at least a part of the comparison circuit 51 areformed. The lower substrate 11C is provided with at least the datastorage unit 52 for storing a time code and the time code transfer unit23. On the intermediate substrate 11B, the remaining circuits of thecomparison circuit 51 that are not arranged on the upper substrate 11Aare formed. The upper substrate 11A and the intermediate substrate 11B,and the intermediate substrate 11B and the lower substrate 11C arebonded by, for example, metal bonding or the like, of Cu—Cu or the like.

FIG. 32 illustrates a circuit arrangement example of each semiconductorsubstrate 11 in a case where the imaging apparatus 1 includes threesemiconductor substrates 11.

In the example of FIG. 32, the circuit disposed on the upper substrate11A is the same as the circuit of the upper substrate 11A illustrated inFIG. 30, the remaining circuits of the comparison circuit 51 aredisposed on the intermediate substrate 11B, and the data storage unit 52and the time code transfer unit 23 are disposed on the lower substrate11C.

In the example illustrated in FIGS. 29 to 32, the judgement unit 401,the bias circuit 501, the DAC 25, and the like can be formed on thelower substrate 11C. Furthermore, a substrate to be further stacked onthe lower substrate 11C may be provided, and the judgement unit 401, thebias circuit 501, the DAC 25, and the like may be formed on thesubstrate.

Furthermore, the imaging apparatus 1 may have a stacked structure, andthe ADC 42 may be configured to be connected to each pixel. For example,a photoelectric conversion element (photodiode 121) may be included inthe first layer, a conversion unit (ADC 42) may be connected withrespect to each photoelectric conversion element, and the conversionunit may be configured to be formed in the second layer below the firstlayer.

Furthermore, a structure including a plurality of image sensors (imagingapparatus 1) having two or more layers may be possible, and each of theplurality of image sensors may be an imaging apparatus 1 that detectsdifferent light, for example, radiation, infrared light, ambient light,or the like.

<Other Configurations>

The present technology is not limited to the scope applied to theconfiguration described above with reference to FIG. 10, for example,and can also be applied to the configuration illustrated below.

FIG. 33 is a diagram illustrating another configuration of the ADC 42and peripheral circuits to which the present technology is applied.According to a comparison with the configuration illustrated in FIG. 10,the configuration illustrated in FIG. 33 is a configuration in which asource follower 702 and a CDS 604 are added between the pixel circuit 41and the ADC 42 (adding unit 303). Furthermore, an adding unit 701 forcontrolling the noise in the source follower 702 and an adding unit 703for controlling the noise in the CDS 604 are also configured to beadded.

The judgement unit 401 controls the amount of noise of the sourcefollower 702, the CDS 604, and the ADC 42 according to the output fromthe ADC 42. The judgement unit 401 controls the amount of noise of atleast one of the source follower 702, the CDS 604, and the ADC 42.

FIG. 33 illustrates the case where the judgement result of the judgementunit 401 is supplied to each of the adding unit 701, the adding unit703, and the adding unit 303, but, for example, the judgement result canbe configured to be supplied only to the adding unit 701 of the sourcefollower 702. Furthermore, the judgement result from the judgement unit401 can be supplied only to the CDS 604 or to the ADC 42 only.

Furthermore, as illustrated in FIG. 33, the judgement result of thejudgement unit 401 may be supplied to the adding unit 701, the addingunit 703, and the adding unit 303 respectively, and the amount of noiseof the source follower 702, the CDS 604, and the ADC 42 may becontrolled respectively. At this time, the same judgement result may besupplied, or different judgement results suitable for each may besupplied.

In the configuration illustrated in FIG. 33, for example, the current ofthe current source of the source follower 702 is controlled, and areduction in noise and a reduction in power consumption are achieved.Furthermore, for example, by controlling the current of the analogelements constituting the CDS 604, noise reduction and power consumptionreduction are achieved. Furthermore, when the current in the ADC 42 iscontrolled as described above, noise reduction and power consumptionreduction are achieved.

FIG. 34 is a diagram illustrating another configuration of the ADC 42and peripheral circuits to which the present technology is applied.According to a comparison with the configuration illustrated in FIG. 10,the configuration illustrated in FIG. 34 is a configuration in which thesource follower 702 is added between the pixel circuit 41 and the ADC 42(adding unit 303). Furthermore, the adding unit 701 for controlling thenoise in the source follower 702 is also configured to be added.

The configuration illustrated in FIG. 34 illustrates a configuration ofthe case where the present technology is applied to a slope-type columnADC. In such a configuration, only one of the source follower 702 andthe ADC 42 can be configured to control the amount of noise.Furthermore, the amount of noise of the source follower 702 and the ADC42 can be configured to be controlled respectively.

In a case where the amount of noise of the source follower 702 and theADC 42 is controlled, regarding the judgement result from the judgementunit 401, the same judgement result may be supplied or differentjudgement results may be supplied.

In the configuration illustrated in FIG. 34, for example, the current ofthe current source of the source follower 702 is controlled, and areduction in noise and a reduction in power consumption are achieved.Furthermore, when the current in the ADC 42 is controlled as describedabove, noise reduction and power consumption reduction are achieved.

FIG. 35 is a diagram illustrating another configuration of the ADC 42and peripheral circuits to which the present technology is applied.According to a comparison with the configuration illustrated in FIG. 10,the configuration illustrated in FIG. 35 is a configuration in which thesource follower 702 is added between the pixel circuit 41 and the ADC 42(adding unit 303). Furthermore, the adding unit 701 for controlling thenoise in the source follower 702 is also configured to be added.Moreover, a judgement unit 711 that controls the ADC 42 according to theoutput from the source follower 702 is configured to be added.

The configuration illustrated in FIG. 35 illustrates a configuration ofthe case where the present technology is applied to an adaptive gainmulti-slope ADC. In such a configuration, only one of the sourcefollower 702 and the ADC 42 can be configured to control the amount ofnoise. Furthermore, the amount of noise of the source follower 702 andthe ADC 42 can be configured to be controlled respectively.

In a case where the amount of noise of the source follower 702 and theADC 42 is controlled, regarding the judgement result from the judgementunit 401, the same judgement result may be supplied or differentjudgement results may be supplied.

In the configuration illustrated in FIG. 35, for example, the current ofthe current source of the source follower 702 is controlled, and areduction in noise and a reduction in power consumption are achieved.Furthermore, when the current in the ADC 42 is controlled as describedabove, noise reduction and power consumption reduction are achieved.

FIG. 36 is a diagram illustrating another configuration of the ADC 42and peripheral circuits to which the present technology is applied.According to a comparison with the configuration illustrated in FIG. 10,the configuration illustrated in FIG. 36 is a configuration in which thesource follower 702 and a gain amplifier 722 are added between the pixelcircuit 41 and the ADC 42 (adding unit 303). Furthermore, the addingunit 701 for controlling the noise in the source follower 702 and anadding unit 721 for controlling the noise in the gain amplifier 722 arealso configured to be added.

The judgement unit 401 controls the amount of noise of each of thesource follower 702, the gain amplifier 722, and the ADC 42 inaccordance with the output from the ADC 42. The judgement unit 401controls the amount of noise of at least one of the source follower 702,the gain amplifier 722, and the ADC 42.

The judgement unit 401 may supply the same judgement result or maysupply different judgement results to the source follower 702, the gainamplifier 722, and the ADC 42.

In the configuration illustrated in FIG. 36, for example, the current ofthe current source of the source follower 702 is controlled, and areduction in noise and a reduction in power consumption are achieved.Furthermore, for example, by controlling the current of the analogelements constituting the gain amplifier 722, noise reduction and powerconsumption reduction are achieved. Furthermore, when the current in theADC 42 is controlled as described above, noise reduction and powerconsumption reduction are achieved.

The present technology can be applied to any of these configurations,and by applying the present technology, the current consumed by ananalog circuit such as a source follower, a gain amplifier, a CDS, anADC, or the like can be variably adjusted adaptively from anAD-converted output signal such that low power can be achieved at highilluminance and low noise can be achieved at low illuminance.

Furthermore, the stacked structure described with reference to FIGS. 29to 22 can be applied to any of these configurations.

<Examples of Application to Electronic Equipment>

The present disclosure is not limited to application to an imagingapparatus. That is, the present disclosure can be generally applied toelectronic equipment using an imaging apparatus in an image capturingunit (photoelectric conversion unit) such as an imaging apparatus suchas a digital still camera, video camera, or the like, a portableterminal apparatus having an imaging function, or a copying machineusing the imaging apparatus for an image reading unit. The imagingapparatus may be in a form of being formed as one chip or may be in amodule form having an imaging function in which an imaging unit and asignal processing unit or an optical system are collectively packaged.

FIG. 37 is a block diagram illustrating a configuration example of animaging apparatus as electronic equipment according to the presentdisclosure.

An imaging apparatus 800 in FIG. 37 includes an optical unit 801including a lens group and the like, an imaging apparatus (imagingdevice) 802 that adopts the configuration of the imaging apparatus 1described above, and a digital signal processor (DSP) circuit 803 thatis a camera signal processing circuit. Furthermore, the imagingapparatus 800 also includes a frame memory 804, a display unit 805, arecording unit 806, an operation unit 807, and a power supply unit 808.The DSP circuit 803, the frame memory 804, the display unit 805, therecording unit 806, the operation unit 807, and the power supply unit808 are connected to each other via a bus line 809.

The optical unit 801 takes in incident light (image light) from asubject and forms an image on an imaging surface of the imagingapparatus 802. The imaging apparatus 802 converts the amount of incidentlight that forms an image on the imaging surface by the optical unit 801into an electric signal in units of pixel, and outputs the electricsignal as a pixel signal.

The display unit 805 includes, for example, a panel-type displayapparatus, e.g., a liquid crystal panel or an organic electroluminescence (EL) panel, and displays a moving image or a still imagecaptured by the imaging apparatus 802. The recording unit 806 records amoving image or a still image captured by the imaging apparatus 802 on arecording medium such as a hard disk, a semiconductor memory, or thelike.

The operation unit 807 issues operation instructions with respect tovarious functions of the imaging apparatus 800 under a user's operation.The power supply unit 808 appropriately supplies various power sources,which are operation power for the DSP circuit 803, the frame memory 804,the display unit 805, the recording unit 806, and the operation unit807, to these supply targets.

As the imaging apparatus 802, the imaging apparatus 1 adopting theabove-described configuration can be used.

The present disclosure is applicable not only to an imaging apparatusbut also to all semiconductor apparatuses having other semiconductorintegrated circuits.

An embodiment of the present disclosure is not limited to theaforementioned embodiment, but various changes may be made within ascope without departing from the gist of the present disclosure.

Although the circuit configuration of each of the above-describedembodiments has been described as a circuit configuration usingelectrons as charges, the present disclosure may be a circuitconfiguration using holes as charges. Furthermore, in each circuitconfiguration described above, it is possible to achieve a circuitconfiguration in which the polarities of the transistors (NMOStransistor and PMOS transistor) are switched. In this case, the controlsignal input to the transistor is a signal in which Hi and Low arereversed.

In each of the embodiments described above, the reference signal REF hasbeen described as a slope signal whose level (voltage) monotonouslydecreases with time, but the reference signal REF may be a slope signalwhose level (voltage) monotonously increases with time.

In addition, the form which combines all or one part of theaforementioned plurality of embodiments can be adopted. A form in whichother embodiments that are not described in the above-describedembodiments are appropriately combined may be provided.

<Application Example for In-Vivo Information Acquisition System>

The technology according to the present disclosure (present technology)is applicable to a variety of products. For example, the technologyaccording to the present disclosure may be applied to an endoscopicsurgery system.

FIG. 38 is a block diagram illustrating an example of a schematicconfiguration of a patient in-vivo information acquisition system usinga capsule endoscope to which the technology according to the presentdisclosure (present technology) can be applied.

An in-vivo information acquisition system 10001 includes a capsuleendoscope 10100 and an external control apparatus 10200.

The capsule endoscope 10100 is swallowed by a patient at the time ofexamination. The capsule endoscope 10100 has an imaging function and awireless communication function, moves inside the organs such as thestomach and the intestine by peristaltic motion or the like until it isspontaneously discharged from the patient, sequentially capture imagesof the inside of the organs (hereinafter also referred to as in-vivoimages) at predetermined intervals, and sequentially wirelesslytransmits information about the in-vivo images to the external controlapparatus 10200 outside the body.

The external control apparatus 10200 comprehensively controls theoperation of the in-vivo information acquisition system 10001.Furthermore, the external control apparatus 10200 receives informationabout the in-vivo image transmitted from the capsule endoscope 10100,and on the basis of the received information about the in-vivo image,generates image data for displaying the in-vivo image on a displayapparatus (not illustrated).

In the in-vivo information acquisition system 10001, in this way, thein-vivo image obtained by capturing the state of the patient's body canbe obtained from time to time until the capsule endoscope 10100 isswallowed and discharged.

The configurations and functions of the capsule endoscope 10100 and theexternal control apparatus 10200 will be described in more detail.

The capsule endoscope 10100 includes a capsule-type housing 10101. Inthe housing 10101, a light source unit 10111, an imaging unit 10112, animage processing unit 10113, a wireless communication unit 10114, apower feeding unit 10115, and a power supply unit 10116, and a controlunit 10117 are accommodated.

The light source unit 10111 includes a light source, for example, alight emitting diode (LED), or the like, and irradiates the imagingfield of the imaging unit 10112 with light.

The imaging unit 10112 includes an image sensor and an optical systemincluding a plurality of lenses provided in the preceding stage of theimage sensor. Reflected light (hereinafter referred to as observationlight) of light emitted to the body tissue to be observed is collectedby the optical system and is incident on the image sensor. In theimaging unit 10112, in the image sensor, the observation light incidentthereon is photoelectrically converted, and an image signalcorresponding to the observation light is generated. The image signalgenerated by the imaging unit 10112 is provided to the image processingunit 10113.

The image processing unit 10113 is configured by a processor such as acentral processing unit (CPU), a graphics processing unit (GPU), or thelike, and performs various types of signal processing on the imagesignal generated by the imaging unit 10112. The image processing unit10113 provides the image signal subjected to signal processing to thewireless communication unit 10114 as RAW data.

The wireless communication unit 10114 performs predetermined processingsuch as modulation processing or the like on the image signal that hasbeen subjected to signal processing by the image processing unit 10113,and transmits the image signal to the external control apparatus 10200via an antenna 10114A. Furthermore, the wireless communication unit10114 receives a control signal related to drive control of the capsuleendoscope 10100 from the external control apparatus 10200 via theantenna antenna 10114A. The wireless communication unit 10114 providesthe control signal received from the external control apparatus 10200 tothe control unit 10117.

The power feeding unit 10115 includes a power receiving antenna coil, apower regeneration circuit that regenerates power from a currentgenerated in the antenna coil, a booster circuit, and the like. In thepower feeding unit 10115, electric power is generated using a so-callednon-contact charging principle.

The power supply unit 10116 is configured by a secondary battery, andstores the power generated by the power feeding unit 10115. In FIG. 38,in order to avoid complication of the drawing, illustration of an arrowor the like indicating a destination of power supply from the powersupply unit 10116 is omitted, but the power stored in the power supplyunit 10116 is supplied to the light source unit 10111, the imaging unit10112, the image processing unit 10113, the wireless communication unit10114, and the control unit 10117, and can be used for driving them.

The control unit 10117 includes a processor such as a CPU, and controlsaccording to a control signal transmitted from the external controlapparatus 10200 to drive the light source unit 10111, the imaging unit10112, the image processing unit 10113, the wireless communication unit10114, and the power feeding unit 10115.

The external control apparatus 10200 is configured by a processor suchas a CPU, a GPU, or the like, a microcomputer or a control board inwhich a processor and a storage element such as a memory are mounted.The external control apparatus 10200 controls the operation of thecapsule endoscope 10100 by transmitting a control signal to the controlunit 10117 of the capsule endoscope 10100 via the antenna 10200A. In thecapsule endoscope 10100, for example, the light irradiation condition onthe observation target in the light source unit 10111 can be changed bya control signal from the external control apparatus 10200. Furthermore,an imaging condition (for example, a frame rate, an exposure value, orthe like in the imaging unit 10112) can be changed by a control signalfrom the external control apparatus 10200. Furthermore, the content ofprocessing in the image processing unit 10113 and the conditions for thewireless communication unit 10114 to transmit an image signal (forexample, a transmission interval, the number of transmission images, orthe like) may be changed by a control signal from the external controlapparatus 10200.

Furthermore, the external control apparatus 10200 performs various typesof image processing on the image signal transmitted from the capsuleendoscope 10100, and generates image data for displaying the capturedin-vivo image on the display apparatus. For example, various signalprocessing such as development processing (demosaic processing),high-image quality processing (band emphasizing processing,super-resolution processing, noise reduction (NR) processing and/orshake correction processing, or the like), and/or magnificationprocessing (electronic zoom processing), may be performed. The externalcontrol apparatus 10200 controls the drive of the display apparatus todisplay the in-vivo image captured on the basis of the generated imagedata. Alternatively, the external control apparatus 10200 may cause thegenerated image data to be recorded on a recording apparatus (notillustrated) or to be printed out by a printing apparatus (notillustrated).

An example of the in-vivo information acquisition system to which thetechnology according to the present disclosure can be applied has beendescribed. The technology according to the present disclosure can beapplied to, for example, any one of the light source unit 10111 to thecontrol unit 10117 among the configurations described above.Specifically, the imaging apparatus 1 including the ADC 42 illustratedin FIG. 3 and the like can be applied to the imaging unit 10112.

<Application Example to Endoscopic Surgery System>

The technology according to the present disclosure (present technology)is applicable to a variety of products. For example, the technologyaccording to the present disclosure may be applied to an endoscopicsurgery system.

FIG. 39 is a diagram illustrating an example of a schematicconfiguration of an endoscopic surgery system to which the technology(present technology) according to the present disclosure can be applied.

FIG. 39 illustrates a situation where an operator (doctor) 11131 isperforming surgery on a patient 11132 on a patient bed 11133 using theendoscopic surgery system 11000. As illustrated, the endoscopic surgerysystem 11000 includes an endoscope 11100, other surgical tools 11110,e.g., a pneumoperitoneum tube 11111, an energy treatment tool 11112, orthe like, a support arm apparatus 11120 supporting the endoscope 11100,and a cart 11200 on which various apparatuses for an endoscopic surgeryare mounted.

The endoscope 11100 includes a lens tube 11101 in which a region of apredetermined length from a tip end, is inserted into the body cavity ofthe patient 11132, and a camera head 11102 connected to a base end ofthe lens tube 11101. In the illustrated example, the endoscope 11100configured as a so-called rigid scope including a rigid lens tube 11101,is illustrated, but the endoscope 11100 may be configured as a so-calledflexible scope including a flexible lens tube.

An opening portion into which an objective lens is fitted, is providedon the tip end of the lens tube 11101. A light source apparatus 11203 isconnected to the endoscope 11100, and light generated by the lightsource apparatus 11203 is guided to the tip end of the lens tube by alight guide provided to extend in the lens tube 11101, and is emittedtowards an observation target in the body cavity of the patient 11132through the objective lens. Note that the endoscope 11100 may be aforward-viewing endoscope, or may be an oblique-viewing endoscope or aside-viewing endoscope.

In the camera head 11102, an optical system and an imaging element areprovided, and reflection light (observation light) from the observationtarget, is condensed in the image sensor by the optical system. Theobservation light is subjected to the photoelectric conversion by theimage sensor, and an electrical signal corresponding to the observationlight, that is, an image signal corresponding to an observation image,is generated. The image signal is transmitted to a camera control unit(CCU) 11201, as RAW data.

The CCU 11201 includes a central processing unit (CPU), a graphicsprocessing unit (GPU), or the like, and integrally controls theoperation of the endoscope 11100 and the display apparatus 11202.Moreover, the CCU 11201 receives the image signal from the camera head11102 and performs various image processing for displaying the imagebased on the image signal, for example, as development processing(demosaic processing) or the like, on the image signal.

The display apparatus 11202 displays an image based on the image signalsubjected to the image processing by the CCU 11201 according to thecontrol from the CCU 11201.

The light source apparatus 11203, for example, includes a light sourcesuch as a light emitting diode (LED) or the like, and supplies theirradiation light at the time of capturing the surgery site to theendoscope 11100.

The input apparatus 11204 is an input interface with respect to theendoscopic surgery system 11000. The user is capable of performing theinput of various information items, or the input of an instruction withrespect to endoscopic surgery system 11000, through the input apparatus11204. For example, the user inputs an instruction or the like to changeconditions of imaging (type of irradiation light, magnification, focallength, and the like) by the endoscope 11100.

The treatment tool control apparatus 11205 controls the driving of theenergy treatment tool 11112 for the cauterization and the incision ofthe tissue, the sealing of the blood vessel, or the like. In order toensure a visual field of the endoscope 11100 and to ensure a workingspace of the surgery operator, the pneumoperitoneum apparatus 11206sends gas into the body cavity through the pneumoperitoneum tube 11111such that the body cavity of the patient 11132 is inflated. The recorder11207 is an apparatus capable of recording various information itemsassociated with the surgery. The printer 11208 is an apparatus capableof printing various information items associated with the surgery, invarious formats such as a text, an image, or a graph.

Note that the light source apparatus 11203 that supplies irradiationlight when capturing the surgical site to the endoscope 11100 can beconfigured from, for example, a white light source configured by an LED,a laser light source, or a combination thereof. In a case where thewhite light source includes a combination of RGB laser light sources, itis possible to control an output intensity and an output timing of eachcolor (each wavelength) with a high accuracy, and thus, it is possibleto adjust a white balance of the captured image with the light sourceapparatus 11203. Furthermore, in this case, laser light from each of theRGB laser light sources is emitted to the observation target in a timedivision manner, and the driving of the image sensor of the camera head11102 is controlled in synchronization with the emission timing, andthus, it is also possible to capture an image corresponding to each ofRGB in a time division manner. According to such a method, it ispossible to obtain a color image without providing a color filter in theimage sensor.

Furthermore, the driving of the light source apparatus 11203 may becontrolled such that the intensity of the light to be output is changedfor each predetermined time. The driving of the image sensor of thecamera head 11102 is controlled in synchronization with a timing whenthe intensity of the light is changed, images are acquired in a timedivision manner, and the images are synthesized, and thus, it ispossible to generate an image of a high dynamic range, without so-calledblack defects and overexposure.

Furthermore, the light source apparatus 11203 may be configured tosupply light of a predetermined wavelength band corresponding to speciallight imaging. In the special light imaging, for example, light of anarrow band is applied, compared to irradiation light at the time ofperforming usual observation by using wavelength dependency of absorbinglight in the body tissue (i.e., white light), and thus, so-called narrowband imaging of capturing a predetermined tissue of a blood vessel orthe like in a superficial portion of a mucous membrane with a highcontrast, is performed. Alternatively, in the special light imaging,fluorescent light imaging of obtaining an image by fluorescent lightgenerated by being irradiated with excited light, may be performed. Inthe fluorescent light imaging, for example, the body tissue isirradiated with the excited light, and the fluorescent light from thebody tissue is observed (autofluorescent light imaging), or a reagentsuch as indian cyanine green (ICG) is locally injected into the bodytissue, and the body tissue is irradiated with excited lightcorresponding to a fluorescent light wavelength of the reagent, andthus, a fluorescent image is obtained. The light source apparatus 11203can be configured to supply the narrow band light and/or the excitedlight corresponding to such special light imaging.

FIG. 40 is a block diagram illustrating an example of a functionalconfiguration of the camera head 11102 and the CCU 11201 illustrated inFIG. 39.

The camera head 11102 includes a lens unit 11401, an imaging unit 11402,a drive unit 11403, a communication unit 11404, and a camera headcontrol unit 11405. The CCU 11201 includes a communication unit 11411,an image processing unit 11412, and a control unit 11413. The camerahead 11102 and the CCU 11201 are connected to be capable of mutualcommunication through a transmission cable 11400.

The lens unit 11401 is an optical system provided in a connectionportion with the lens tube 11101. Observation light incorporated from atip end of the lens tube 11101 is guided to the camera head 11102 and isincident on the lens unit 11401. The lens unit 11401 includes acombination of a plurality of lenses including a zoom lens and a focuslens.

The image sensor constituting the imaging unit 11402 may be one(so-called single plate type) or plural (so-called multi-plate type). Ina case where the imaging unit 11402 is configured as a multi-plate type,for example, image signals corresponding to RGB may be generated by eachimage sensor, and a color image may be obtained by combining them.Alternatively, the imaging unit 11402 may include a pair of imagesensors for respectively acquiring right-eye and left-eye image signalscorresponding to 3D (dimensional) display. The 3D display is performed,and thus, the surgery operator 11131 is capable of more accuratelygrasping the depth of the biological tissue in the surgery portion. Notethat, in a case where the imaging unit 11402 is configured by amulti-plate type configuration, a plurality of lens units 11401 may beprovided corresponding to each of the image sensor.

Furthermore, the imaging unit 11402 may not be necessarily provided inthe camera head 11102. For example, the imaging unit 11402 may beprovided immediately after the objective lens, in the lens tube 11101.

The driving unit 11403 includes an actuator, and moves the zoom lens andthe focus lens of the lens unit 11401 along the optical axis by apredetermined distance, according to the control from the camera headcontrol unit 11405. Therefore, it is possible to suitably adjust themagnification and the focal point of the image imaged by the imagingunit 11402.

The communication unit 11404 includes a communication apparatus fortransmitting and receiving various information items with respect to theCCU 11201. The communication unit 11404 transmits the image signalobtained from the imaging unit 11402 to the CCU 11201 through thetransmission cable 11400, as the RAW data.

Furthermore, the communication unit 11404 receives a control signal forcontrolling the driving of the camera head 11102 from the CCU 11201 andsupplies the control signal to the camera head control unit 11405. Thecontrol signal, for example, includes information associated with theimaging condition, such as information of designating a frame rate ofthe imaged image, information of designating an exposure value at thetime of the imaging, and/or information of designating the magnificationand the focal point of the imaged image.

Note that the imaging conditions such as the frame rate, exposure value,magnification, and focus described above may be appropriately designatedby the user, or may be automatically set by the control unit 11413 ofthe CCU 11201 on the basis of the acquired image signal. In the lattercase, a so-called auto exposure (AE) function, an auto focus (AF)function, and an auto white balance (AWB) function are provided in theendoscope 11100.

The camera head control unit 11405 controls the driving of the camerahead 11102 on the basis of the control signal from the CCU 11201received through the communication unit 11404.

The communication unit 11411 includes a communication apparatus fortransmitting and receiving various information items with respect to thecamera head 11102. The communication unit 11411 receives the imagesignal to be transmitted from the camera head 11102, through thetransmission cable 11400.

Furthermore, the communication unit 11411 transmits the control signalfor controlling the driving of the camera head 11102 to the camera head11102. The image signal and the control signal can be transmitted byelectrical communication, optical communication, or the like.

The image processing unit 11412 performs various image processing on theimage signal which is the RAW data transmitted from the camera head11102.

The control unit 11413 performs various types of control related toimaging of the surgical site or the like by the endoscope 11100 anddisplay of a captured image obtained by imaging of the surgical site orthe like. For example, the control unit 11413 generates the controlsignal for controlling the driving of the camera head 11102.

Furthermore, the control unit 11413 causes the display apparatus 11202to display the captured image of the surgery site or the like on thebasis of the image signal subjected to the image processing by the imageprocessing unit 11412. At this time, the control unit 11413 mayrecognize various objects in the captured image by using various imagerecognition technologies. For example, the control unit 11413 detectsthe shape, the color, or the like of the edge of the object included inthe captured image, and thus, it is possible to recognize a surgicaltool such as forceps, a specific biological portion, bleed, mist at thetime of using the energy treatment tool 11112, and the like When thecaptured image is displayed on the display apparatus 11202, the controlunit 11413 may display various surgery support information items to besuperimposed on the image of the surgery site, by using a recognitionresult. Surgery support information is displayed in a superimposedmanner and presented to the operator 11131, thereby reducing the burdenon the operator 11131 and allowing the operator 11131 to proceed withsurgery reliably.

The transmission cable 11400 connecting the camera head 11102 and theCCU 11201 together, is an electrical signal cable corresponding to thecommunication of the electrical signal, an optical fiber correspondingto the optical communication, or a composite cable thereof.

Here, in the illustrated example, the communication is performed in awired manner, by using the transmission cable 11400, but thecommunication between the camera head 11102 and the CCU 11201, may beperformed in a wireless manner.

An example of the endoscopic surgery system to which the technologyaccording to the present disclosure can be applied, has been described.Among the configurations described above, the technology according tothe present disclosure can be applied to the endoscope 11100, (theimaging unit 11402 of) the camera head 11102, (the image processing unit11412 of) the CCU 11201, and the like. Specifically, the imagingapparatus 1 including the ADC 42 illustrated in FIG. 3 and the like canbe applied to the imaging unit 10402.

Note that, here, although an endoscopic surgery system has beendescribed as an example, the technology according to the presentdisclosure may be applied to, for example, a microscope surgery systemand the like.

<Application Examples to Mobile Objects>

The technology according to the present disclosure (present technology)is applicable to a variety of products. For example, the technologyaccording to the present disclosure may be implemented as apparatusesmounted on any type of movable bodies such as automobiles, electricvehicles, hybrid electric vehicles, motorcycles, bicycles, personalmobilities, airplanes, drones, ships, robots.

FIG. 41 is a block diagram illustrating a schematic configurationexample of a vehicle control system, which is an example of a movablebody control system to which the technology according to the presentdisclosure can be applied.

The vehicle control system 12000 includes a plurality of electroniccontrol units connected via a communication network 12001. In theexample illustrated in FIG. 41, the vehicle control system 12000includes a drive line control unit 12010, a body system control unit12020, a vehicle outside information detecting unit 12030, a vehicleinside information detecting unit 12040, and an integrated control unit12050. Furthermore, a microcomputer 12051, an audio and image outputunit 12052, and an in-vehicle network interface (I/F) 12053 areillustrated as functional configurations of the integrated control unit12050.

The drive line control unit 12010 controls the operation of apparatusesrelated to the drive line of the vehicle in accordance with a variety ofprograms. For example, the drive line control unit 12010 functions as acontrol apparatus for a driving force generating apparatus such as aninternal combustion engine or a driving motor that generates the drivingforce of the vehicle, a driving force transferring mechanism thattransfers the driving force to wheels, a steering mechanism that adjuststhe steering angle of the vehicle, a braking apparatus that generatesthe braking force of the vehicle, and the like.

The body system control unit 12020 controls the operations of a varietyof apparatuses attached to the vehicle body in accordance with a varietyof programs. For example, the body system control unit 12020 functionsas a control apparatus for a keyless entry system, a smart key system, apower window apparatus, or a variety of lights such as a headlight, abackup light, a brake light, a blinker, or a fog lamp. In this case, thebody system control unit 12020 can receive radio waves transmitted froma portable device that serves instead of the key or signals of a varietyof switches. The body system control unit 12020 accepts input of theseradio waves or signals, and controls the vehicle door lock apparatus,the power window apparatus, the lights, or the like.

The vehicle outside information detecting unit 12030 detects informationregarding the outside of the vehicle including the vehicle controlsystem 12000. For example, the imaging unit 12031 is connected to thevehicle outside information detecting unit 12030. The vehicle outsideinformation detecting unit 12030 causes the imaging unit 12031 tocapture images of the outside of the vehicle, and receives the capturedimage. The vehicle outside information detecting unit 12030 may performprocessing of detecting an object such as a person, a car, an obstacle,a traffic sign, or a letter on a road, or processing of detecting thedistance on the basis of the received image.

The imaging unit 12031 is an optical sensor that receives light andoutputs an electric signal corresponding to the amount of receivedlight. The imaging unit 12031 can output the electric signal as theimage or output the electric signal as ranging information. Furthermore,the light received by the imaging unit 12031 may be visible light orinvisible light such as infrared light.

The vehicle inside information detecting unit 12040 detects informationof the inside of the vehicle. The vehicle inside information detectingunit 12040 is connected, for example, to a driver state detecting unit12041 that detects the state of the driver. The driver state detectingunit 12041 includes, for example, a camera that images a driver, and thevehicle inside information detecting unit 12040 may compute the degreeof the driver's tiredness or the degree of the driver's concentration ordetermine whether or not the driver has a doze, on the basis ofdetection information input from the driver state detecting unit 12041.

The microcomputer 12051 can calculate a control target value of thedriving force generating apparatus, the steering mechanism, or thebraking apparatus on the basis of information regarding the inside andoutside of the vehicle acquired by the vehicle outside informationdetecting unit 12030 or the vehicle inside information detecting unit12040, and output a control instruction to the drive line control unit12010. For example, the microcomputer 12051 can perform cooperativecontrol for the purpose of executing the functions of the advanceddriver assistance system (ADAS) including vehicle collision avoidance orimpact reduction, follow-up driving based on the inter-vehicle distance,constant vehicle speed driving, vehicle collision warning, vehicle lanedeviation warning, or the like.

Furthermore, the microcomputer 12051 can perform cooperative control forthe purpose of automatic driving or the like for autonomous runningwithout depending on the driver's operation through control of thedriving force generating apparatus, the steering mechanism, the brakingapparatus, or the like on the basis of information around the vehicleacquired by the vehicle outside information detecting unit 12030 or thevehicle inside information detecting unit 12040.

Furthermore, the microcomputer 12051 can output a control instruction tothe body system control unit 12030 on the basis of the informationoutside the vehicle obtained by the vehicle outside informationdetecting unit 12030. For example, the microcomputer 12051 can performthe cooperative control for realizing glare protection such ascontrolling the head light according to a position of a precedingvehicle or an oncoming vehicle detected by the vehicle outsideinformation detecting unit 12030 to switch a high beam to a low beam.

The audio and image output unit 12052 transmits an output signal of atleast one of a sound or an image to an output apparatus capable ofvisually or aurally notifying a passenger of the vehicle or the outsideof the vehicle of information. In the example of FIG. 41, an audiospeaker 12061, a display unit 12062, and an instrument panel 12063 areexemplified as the output apparatus. For example, the display unit 12062may include at least one of an onboard display or a head-up display.

FIG. 42 is a view illustrating an example of an installation position ofthe imaging unit 12031.

In FIG. 42, imaging units 12101, 12102, 12103, 12104, and 12105 areprovided as the imaging unit 12031.

The imaging units 12101, 12102, 12103, 12104 and 12105 are positioned,for example, at the front nose, a side mirror, the rear bumper, the backdoor, the upper part of the windshield in the vehicle compartment, orthe like of a vehicle 12100. The imaging unit 12101 attached to thefront nose and the imaging unit 12105 attached to the upper part of thewindshield in the vehicle compartment mainly acquire images of the areaahead of the vehicle 12100. The imaging units 12102 and 12103 attachedto the side mirrors mainly acquire images of the areas on the sides ofthe vehicle 12100. The imaging unit 12104 attached to the rear bumper orthe back door mainly acquires images of the area behind the vehicle12100. The imaging unit 12105 attached to the upper part of thewindshield in the vehicle compartment is used mainly to detect apreceding vehicle, a pedestrian, an obstacle, a traffic light, a trafficsign, a lane, or the like.

Note that FIG. 42 illustrates an example of the respective imagingranges of the imaging units 12101 to 12104. An imaging range 12111represents the imaging range of the imaging unit 12101 attached to thefront nose. Imaging ranges 12112 and 12113 respectively represent theimaging ranges of the imaging units 12102 and 12103 attached to the sidemirrors. An imaging range 12114 represents the imaging range of theimaging unit 12104 attached to the rear bumper or the back door. Forexample, overlaying image data captured by the imaging units 12101 to12104 offers an overhead image that looks down on the vehicle 12100.

At least one of the imaging units 12101 to 12104 may have a function ofobtaining distance information. For example, at least one of the imagingunits 12101 to 12104 may be a stereo camera including a plurality ofimage sensors, or may be an image sensor having pixels for phasedifference detection.

For example, the microcomputer 12051 may extract especially a closestthree-dimensional object on a traveling path of the vehicle 12100, thethree-dimensional object traveling at a predetermined speed (forexample, 0 km/h or higher) in a direction substantially the same as thatof the vehicle 12100 as the preceding vehicle by determining a distanceto each three-dimensional object in the imaging ranges 12111 to 12114and change in time of the distance (relative speed relative to thevehicle 12100) on the basis of the distance information obtained fromthe imaging units 12101 to 12104. Moreover, the microcomputer 12051 canset an inter-vehicle distance to be secured in advance from thepreceding vehicle, and can perform automatic brake control (includingfollow-up stop control), automatic acceleration control (includingfollow-up start control) and the like. In this manner, it is possible toperform the cooperative control for realizing automatic driving or thelike to autonomously travel independent from the operation of thedriver.

For example, the microcomputer 12051 can extract three-dimensionalobject data regarding the three-dimensional object while sorting thedata into a two-wheeled vehicle, a regular vehicle, a large vehicle, apedestrian, and other three-dimensional object such as a utility pole onthe basis of the distance information obtained from the imaging units12101 to 12104 and use the data for automatically avoiding obstacles.For example, the microcomputer 12051 discriminates obstacles around thevehicle 12100 into an obstacle visibly recognizable to a driver of thevehicle 12100 and an obstacle difficult to visually recognize. Then, themicrocomputer 12051 determines a collision risk indicating a degree ofrisk of collision with each obstacle, and when the collision risk isequal to or higher than a set value and there is a possibility ofcollision, the microcomputer 12051 can perform driving assistance foravoiding the collision by outputting an alarm to the driver via theaudio speaker 12061 and the display unit 12062 or performing forceddeceleration or avoidance steering via the drive line control unit12010.

At least one of the imaging units 12101 to 12104 may be an infraredcamera for detecting infrared rays. For example, the microcomputer 12051can recognize a pedestrian by determining whether or not there is apedestrian in the captured images of the imaging units 12101 to 12104.Such pedestrian recognition is carried out, for example, by a procedureof extracting feature points in the captured images of the imaging units12101 to 12104 as infrared cameras and a procedure of performing patternmatching processing on a series of feature points indicating an outlineof an object to discriminate whether or not the object is a pedestrian.When the microcomputer 12051 determines that there is a pedestrian inthe captured images of the imaging units 12101 to 12104 and recognizesthe pedestrian, the audio and image output unit 12052 controls thedisplay unit 12062 to superimpose a rectangular contour for emphasis onthe recognized pedestrian. Furthermore, the audio and image output unit12052 may control the display unit 12062 to display icons or the likeindicating pedestrians at desired positions.

An example of the vehicle control system to which the technologyaccording to the present disclosure is applicable is heretoforedescribed. The technology according to the present disclosure can beapplied, for example, to the imaging unit 12031 and the like among theconfigurations described above. Specifically, the imaging apparatus 1including the ADC 42 illustrated in FIG. 3 and the like can be appliedto the imaging unit 12031.

Note that, in the present specification, the system represents theentire apparatus configured by a plurality of apparatuses.

Note that the effects described in the present description are merelyillustrative and are not limitative, and other effects may be provided.

Note that the embodiment of the present technology is not limited to theaforementioned embodiments, but various changes may be made within thescope not departing from the gist of the present technology.

Note that the present technology may be configured as below.

(1)

An imaging apparatus including:

a photoelectric conversion element;

a conversion unit configured to convert a signal from the photoelectricconversion element into a digital signal;

a bias circuit configured to supply a bias current for controllingcurrent flowing through an analog circuit in the conversion unit; and

a control unit configured to control the bias circuit on the basis of anoutput signal from the conversion unit, in which at start of transfer ofa charge from the photoelectric conversion element, the control unitboosts a voltage at a predetermined position of the analog circuit.

(2)

The imaging apparatus according to (1), in which the conversion unitconverts the signal from the photoelectric conversion element into thedigital signal using a slope signal whose level monotonously decreaseswith time.

(3)

The imaging apparatus according to (1) or (2), in which the control unitperforms control to reduce the current flowing through the analogcircuit in a case where the level of the output signal is large.

(4)

The imaging apparatus according to any of (1) to (3), in which thecontrol unit performs control to increase the current flowing throughthe analog circuit in a case where the level of the output signal issmall.

(5)

The imaging apparatus according to any of (1) to (4), in which thevoltage at the predetermined position of the analog circuit is a voltageof a floating diffusion layer.

(6)

The imaging apparatus according to any of (1) to (5), in which

the bias circuit includes a switch, and

the control unit controls the switch so that the bias current from thebias circuit is not supplied to the analog circuit at the start oftransfer of the charge from the photoelectric conversion element.

(7)

The imaging apparatus according to (6), in which the switch is connectedto a ground side at the start of transfer of the charge from thephotoelectric conversion element.

(8)

The imaging apparatus according to (6), in which the bias circuitincludes a source follower circuit.

(9)

The imaging apparatus according to any of (1) to (5), further including:

a wiring configured to apply a voltage to the predetermined position ofthe analog circuit, in which

a voltage is applied to the wiring at the start of transfer of thecharge from the photoelectric conversion element.

(10)

The imaging apparatus according to any of (1) to (5), further including:

a transistor configured to bring a portion receiving supply from thebias circuit and the predetermined position of the analog circuit into aconnection or disconnection state, in which

at the start of transfer of the charge from the photoelectric conversionelement, the transistor is brought into the disconnection state.

(11)

Electronic equipment including:

an imaging apparatus including:

-   -   a photoelectric conversion element;    -   a conversion unit configured to convert a signal from the        photoelectric conversion element into a digital signal;    -   a bias circuit configured to supply a bias current for        controlling current flowing through an analog circuit in the        conversion unit; and    -   a control unit configured to control the bias circuit on the        basis of an output signal from the conversion unit, in which

at start of transfer of a charge from the photoelectric conversionelement, the control unit boosts a voltage at a predetermined positionof the analog circuit.

REFERENCE SIGNS LIST

-   1 Imaging apparatus-   21 Pixel-   22 Pixel array unit-   23 Time code transfer unit-   25 DAC-   26 Time code generation unit-   28 Output unit-   41 Pixel circuit-   42 ADC-   51 Comparison circuit-   52 Data storage unit-   61 Differential input circuit-   62 Voltage conversion circuit-   63 Positive feedback circuit-   71 Latch control circuit-   72 Latch storage unit-   81 to 87, 91 Transistor-   101 to 105, 111 to 113 Transistor-   401 Judgement unit-   501 Bias circuit-   511 Transistor-   512 Current source-   531 Bias circuit-   541, 542 Switch-   551 Parasitic capacitance-   552 Current source-   571 Bias circuit-   581 Transistor-   582 Variable current source-   583 Transistor-   611 Wiring-   612 Parasitic capacitance-   631 Transistor-   701 Adding unit-   702 Source follower-   703 Adding unit-   721 Adding unit-   722 Gain amplifier

1. A light detecting device, comprising: a first substrate thatincludes: a plurality of pixels coupled to a floating diffusion; and afirst part of a differential input circuit shared by the plurality ofpixels; a second substrate laminated to the first substrate, wherein thesecond substrate includes: a second part of the differential inputcircuit coupled to the first part of the differential input circuit; afeedback circuit coupled to the second part of the differential inputcircuit; and a data storage unit coupled to the feedback circuit; and awiring, wherein the floating diffusion is boosted by a voltage suppliedto the wiring.
 2. The light detecting device according to claim 1,wherein the first part of the differential input circuit includes afirst input and a second input, the first input is coupled to theplurality of pixels, and the second input is coupled to adigital-to-analog converter that controls voltages of a referencesignal.
 3. The light detecting device according to claim 2, wherein thereference signal is a slope signal, and a level of the reference signalmonotonously decreases with a time.
 4. The light detecting deviceaccording to claim 3, further comprising a comparison circuit thatincludes the differential input circuit and the feedback circuit,wherein the comparison circuit is configured to: compare a first signalreceived at the first input with a second signal received at the secondinput; and output an output signal as a result of the comparison.
 5. Thelight detecting device according to claim 4, wherein the feedbackcircuit is configured to increase a transition speed of the outputsignal of the comparison circuit.
 6. The light detecting deviceaccording to claim 5, wherein the data storage unit includes a latchstorage unit, and the latch storage unit is configured to store a timecode based on the output signal.
 7. The light detecting device accordingto claim 6, further comprising a time code transfer unit configured tosupply the time code, wherein the time code transfer unit extends to acolumn direction of the plurality of pixels.
 8. The light detectingdevice according to claim 7, wherein the time code is a Gray code. 9.The light detecting device according to claim 8, wherein the firstsubstrate and the second substrate are electrically connected by a metalbonding.
 10. The light detecting device according to claim 9, whereinthe first part of the differential input circuit and the second part ofthe differential input circuit are electrically connected by the metalbonding.
 11. A light detecting device, comprising: a first substratethat includes: a plurality of pixels; and a first part of a differentialinput circuit shared by the plurality of pixels; and a second substratelaminated to the first substrate, wherein the second substrate includes:a second part of the differential input circuit coupled to the firstpart of a differential input circuit; a feedback circuit coupled to thesecond part of the differential input circuit; and a data storage unitcoupled to the feedback circuit, wherein the first part of thedifferential input circuit and the second part of the differential inputcircuit are electrically connected by a metal bonding.
 12. The lightdetecting device according to claim 11, wherein the first part of thedifferential input circuit includes a first input and a second input,the first input is coupled to the plurality of pixels, and the secondinput is coupled to a digital-to-analog converter that controls voltagesof a reference signal.
 13. The light detecting device according to claim12, wherein the reference signal is a slope signal, and a level of thereference signal monotonously decreases with a time.
 14. The lightdetecting device according to claim 13, further comprising a comparisoncircuit that includes the differential input circuit and the feedbackcircuit, wherein the comparison circuit is configured to: compare afirst signal received at the first input with a second signal receivedat the second input, and output an output signal as a result of thecomparison.
 15. The light detecting device according to claim 14,wherein the feedback circuit is configured to increase a transitionspeed of the output signal of the comparison circuit.
 16. The lightdetecting device according to claim 15, wherein the data storage unitincludes a latch storage unit, and the latch storage unit is configuredto store a time code based on the output signal.
 17. The light detectingdevice according to claim 16, further comprising a time code transferunit configured to supply the time code, wherein the time code transferunit extends to a column direction of the plurality of pixels.
 18. Thelight detecting device according to claim 17, wherein the time code is aGray code.
 19. The light detecting device according to claim 18, whereinthe first substrate and the second substrate are electrically connectedby the metal bonding.
 20. The light detecting device according to claim19, further comprising a wiring, wherein a floating diffusion is coupledto the plurality of pixels, and the floating diffusion is boosted by avoltage supplied to the wiring.
 21. A light detecting device,comprising: a first substrate that includes: a plurality of pixelsincluding a specific pixel; and a first part of a differential inputcircuit coupled to a specific pixel; and a second substrate laminated tothe first substrate, wherein the second substrate includes: a secondpart of the differential input circuit coupled to the first part of adifferential input circuit; a feedback circuit coupled to the secondpart of the differential input circuit; and a data storage unit coupledto the feedback circuit, wherein the first part of the differentialinput circuit and the second part of the differential input circuit areelectrically connected by a metal bonding.
 22. The light detectingdevice according to claim 21, wherein the first part of the differentialinput circuit includes a first input and a second input, the first inputis coupled to the specific pixel, and the second input is connectedcoupled to a digital-to-analog converter that controls voltages of areference signal.
 23. The light detecting device according to claim 22,wherein the reference signal is a slope signal, and a level of thereference signal monotonously decreases with a time.
 24. The lightdetecting device according to claim 23, further comprising a comparisoncircuit that includes the differential input circuit and the feedbackcircuit, wherein the comparison circuit is configured to: compare afirst signal received at the first input with a second signal receivedat the second input, and output an output signal as a result of thecomparison.
 25. The light detecting device according to claim 24,wherein the feedback circuit is configured to increase a transitionspeed of the output signal of the comparison circuit.
 26. The lightdetecting device according to claim 25, wherein the data storage unitincludes a latch storage unit, and the latch storage unit is configuredto store a time code based on the output signal.
 27. The light detectingdevice according to claim 26, further comprising a time code transferunit configured to supply the time code, wherein the time code transferunit extends to a column direction of the plurality of pixels.
 28. Thelight detecting device according to claim 27, wherein the time code is aGray code.
 29. The light detecting device according to claim 28, whereinthe first substrate and the second substrate are electrically connectedby the metal bonding.
 30. The light detecting device according to claim29, further comprising a wiring, wherein a floating diffusion is coupledto the specific pixel, and the floating diffusion is boosted by avoltage supplied to the wiring.